media: ti-vpe: cal: Fix compilation on 32-bit ARM

When compiled on 32-bit ARM, the CAL driver fails with the FIELD_PREP()
macro complaining that the mask is not constant. While all callers of
the inline cal_write_field() function pass a constant mask, the mask
parameter itself is a variable, which likely doesn't please the
compiler.

Fix it by replacing FIELD_PREP() with a manual implementation.

Fixes: 50797fb30b95 ("media: ti-vpe: cal: Turn reg_(read|write)_field() into inline functions")
Signed-off-by: Laurent Pinchart <[e-mail]>
Reviewed-by: Sakari Ailus <[e-mail]>
Reported-by: Sakari Ailus <[e-mail]>
Reviewed-by: Tomi Valkeinen <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/platform/ti-vpe/cal.h

···
 	u32 val = cal_read(cal, offset);
 
 	val &= ~mask;
-	val |= FIELD_PREP(mask, value);
+	val |= (value << __ffs(mask)) & mask;
 	cal_write(cal, offset, val);
 }