staging: rts5208: make some vars to lower case to keep the style consistent

This patch fixes the checkpatch.pl warning:

WARNING: Comparisons should place the constant on the right side of the test

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>