drm/mgag200: Clear <page> field during MM init

The modesetting code initialized the memory-related register CRTCEXT4.
Move this code to MM initialization.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200730102844.10995-7-tzimmermann@suse.de

drivers/gpu/drm/mgag200/mgag200_mm.c

@@ -94,6 +94,8 @@ int mgag200_mm_init(struct mga_device *mdev)
 	resource_size_t start, len;
 	int ret;
 
+	WREG_ECRT(0x04, 0x00);
+
 	misc = RREG8(MGA_MISC_IN);
 	misc |= MGAREG_MISC_RAMMAPEN |
 		MGAREG_MISC_HIGH_PG_SEL;

drivers/gpu/drm/mgag200/mgag200_mode.c

@@ -946,7 +946,7 @@ static void mgag200_set_dac_regs(struct mga_device *mdev)
 
 static void mgag200_init_regs(struct mga_device *mdev)
 {
-	u8 crtc11, crtcext4, misc;
+	u8 crtc11, misc;
 
 	mgag200_set_dac_regs(mdev);
 
@@ -961,10 +961,6 @@ static void mgag200_init_regs(struct mga_device *mdev)
 	WREG_CRT(14, 0);
 	WREG_CRT(15, 0);
 
-	crtcext4 = 0x00;
-
-	WREG_ECRT(0x04, crtcext4);
-
 	RREG_CRT(0x11, crtc11);
 	crtc11 &= ~(MGAREG_CRTC11_CRTCPROTECT |
 		    MGAREG_CRTC11_VINTEN |