platform/chrome: cros_ec_lpc: remove redundant pointer request

Pointer request is being assigned but never used, so remove it. Cleans
up the clang warning:

drivers/platform/chrome/cros_ec_lpc.c:68:2: warning: Value stored to
'request' is never read

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Benson Leung <bleung@chromium.org>