mwifiex: send firmware initialization commands synchronously

The driver will send some commands to firmware during the
initialization. Currently these commands are sent asynchronously,
which means that we firstly insert all of them to a pre-allocated
command queue, and then start to process them one by one. The
command queue will soon be exhausted if we keep adding new
initialization commands.

This issue can be resolved by sending initialization commands
synchronously because each command is consumed and the buffer is
recycled before queuing next command.

Signed-off-by: Stone Piao <piaoyun@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>