Staging: winbond: Fix Sparse Warnings in reg.c

This patch fixes the Sparse Warnings "symbol was
not declared. Should it be static?" and "defined
but not used [-Wunused-variable]"
in reg.c

Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>