char: xilinx_hwicap: Fold hwicap_remove() into only caller

hwicap_remove() is only called by hwicap_drv_remove(). Simplify by
unrolling the former into the latter function.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Michal Simek <michal.simek@amd.com>
Message-ID: <20230605092047.50472-1-u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>