[PATCH] airo.c: check returned values

create_proc_entry() can fail and return NULL in setup_proc_entry(), the
result must be checked before dereferencing. (Coverity ID 1443)

init_wifidev() & setup_proc_entry() can also fail in _init_airo_card().

This adds the checks & cleanup code and removes some whitespace.

Signed-off-by: Florin Malita <fmalita@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>