mwifiex: remove redundant goto exit_remove statement

The check for 'priv' pointer is redundant. 'priv' won't
be used later in this routine.

Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>