staging: vt6655: remove some redundant variables

Variables rx_sts, sq, frame and is_pspoll are being assigned but are
never used hence they are redundant and can be removed.

Cleans up clang warnings:
warning: variable 'sq' set but not used [-Wunused-but-set-variable]
warning: variable 'rx_sts' set but not used [-Wunused-but-set-variable]
warning: variable 'frame' set but not used [-Wunused-but-set-variable]
warning: variable 'is_pspoll' 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>