video: fbdev: s3c-fb: remove redundant initialization of pointer bufs

Pointer bufs is being initialized with a value that is never read, it
is being re-assigned with a different value later on. The assignment
is redundant and can be removed. Cleans up clang-scan warning:

drivers/video/fbdev/s3c-fb.c:492:16: warning: Value stored to 'buf'
during its initialization is never read [deadcode.DeadStores]
        void __iomem *buf = regs;

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20211230160626.404072-1-colin.i.king@gmail.com