drm/r128: Fix undefined behavior due to shift overflowing the constant

Fix:

  drivers/gpu/drm/r128/r128_cce.c: In function ‘r128_do_init_cce’:
  drivers/gpu/drm/r128/r128_cce.c:417:2: error: case label does not reduce to an integer constant
    case R128_PM4_64BM_64VCBM_64INDBM:
    ^~~~
  drivers/gpu/drm/r128/r128_cce.c:418:2: error: case label does not reduce to an integer constant
    case R128_PM4_64PIO_64VCPIO_64INDPIO:
    ^~~~

See https://lore.kernel.org/r/YkwQ6%[email protected] for the gory
details as to why it triggers with older gccs only.

Reviewed-by: Randy Dunlap <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Alex Deucher <[email protected]>
Cc: [email protected]
Signed-off-by: Daniel Vetter <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

drivers/gpu/drm/r128/r128_drv.h

@@ -300,8 +300,8 @@ extern long r128_compat_ioctl(struct file *filp, unsigned int cmd,
 #	define R128_PM4_64PIO_128INDBM		(5  << 28)
 #	define R128_PM4_64BM_128INDBM		(6  << 28)
 #	define R128_PM4_64PIO_64VCBM_64INDBM	(7  << 28)
-#	define R128_PM4_64BM_64VCBM_64INDBM	(8  << 28)
-#	define R128_PM4_64PIO_64VCPIO_64INDPIO	(15 << 28)
+#	define R128_PM4_64BM_64VCBM_64INDBM	(8U  << 28)
+#	define R128_PM4_64PIO_64VCPIO_64INDPIO	(15U << 28)
 #	define R128_PM4_BUFFER_CNTL_NOUPDATE	(1  << 27)
 
 #define R128_PM4_BUFFER_WM_CNTL		0x0708