mwifiex: fix a cut-n-paste error in adhoc-start

The 'else if' branch never gets the chance as its condition
matches 'if' branch's.

Reported-by: David Binderman <dcb314@hotmail.com>
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>