staging: sm750fb: rename camel case variable

Rename regValue to reg_value to follow kernel coding style.

Signed-off-by: Ahmet Sezgin Duran <ahmet@sezginduran.net>
Link: https://lore.kernel.org/r/20250912162627.95010-1-ahmet@sezginduran.net


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>