[Keyboard] Update dz60rgb default keymap (#12488)

The keymap for this PCB as of April 5, 2020 has a 4rth, largely superfluous layer, creating a total of 5 layers.

When ported to VIA, this results in a layer that users can access but cannot edit. I propose removing this layer completely along with it's access from the default.

keyboards/dztech/dz60rgb/keymaps/default/keymap.c

@@ -13,7 +13,7 @@ const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
         _______, _______, KC_UP,   _______, _______, _______, KC_CALC, _______, KC_INS,  _______, KC_PSCR, KC_SLCK, KC_PAUS, RESET,
         _______, KC_LEFT, KC_DOWN, KC_RGHT, _______, _______, _______, _______, _______, _______, KC_HOME, KC_PGUP,          EEP_RST,
         _______,          _______, _______, _______, _______, _______, NK_TOGG, _______, _______, KC_END,  KC_PGDN, KC_VOLU, KC_MUTE,
-        _______, _______, _______,                            TO(4),                     _______, _______, KC_MPRV, KC_VOLD, KC_MNXT
+        _______, _______, _______,                            _______,                   _______, _______, KC_MPRV, KC_VOLD, KC_MNXT
     ),
     [2] = LAYOUT(
         _______, KC_F1,   KC_F2,   KC_F3,   KC_F4,   KC_F5,   KC_F6,   KC_F7,   KC_F8,   KC_F9,   KC_F10,  KC_F11,  KC_F12,  KC_DEL,
@@ -28,12 +28,5 @@ const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
         _______, KC_P4,   KC_P5,   KC_P6,   _______, _______, _______, _______, KC_P4,   KC_P5,   KC_P6,   _______,          KC_PENT,
         _______,          KC_P1,   KC_P2,   KC_P3,   _______, _______, _______, _______, KC_P1,   KC_P2,   KC_P3,   _______, _______,
         _______, KC_P0,   KC_PDOT,                            KC_PENT,                   KC_P0,   KC_PDOT, _______, _______, _______
-    ),
-    [4] = LAYOUT(
-        KC_GESC,        KC_1,    KC_2,    KC_3,    KC_4,    KC_5,    KC_6,    KC_7,    KC_8,    KC_9,    KC_0,    KC_MINS,         KC_EQL,  KC_BSPC,
-        KC_TAB,         KC_Q,    KC_W,    KC_E,    KC_R,    KC_T,    KC_Y,    KC_U,    KC_I,    KC_O,    KC_P,    KC_LBRC,         KC_RBRC, KC_BSLS,
-        CTL_T(KC_CAPS), KC_A,    KC_S,    KC_D,    KC_F,    KC_G,    KC_H,    KC_J,    KC_K,    KC_L,    KC_SCLN, KC_QUOT,                  KC_ENT,
-        KC_LSFT,                 KC_Z,    KC_X,    KC_C,    KC_V,    KC_B,    KC_N,    KC_M,    KC_COMM, KC_DOT,  RSFT_T(KC_SLSH), KC_UP,   LT(2, KC_DEL),
-        KC_LCTL,        KC_LALT, KC_LGUI,                            KC_SPC,                    KC_RALT, TO(0),   KC_LEFT,         KC_DOWN, KC_RGHT
     )
 };