staging: gdm724x: redundant variables idProduct and idVendor

Variable idProduct and idVendor are being assigned but are never used
hence they are redundant and can be removed.

Cleans up clang warnings:
warning: variable 'idProduct' set but not used [-Wunused-but-set-variable]
warning: variable 'idVendor' set but not used [-Wunused-but-set-variable]

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>