[BUG] ssb: Possible sleep-in-atomic bugs in ssb_pcmcia_read8

[Jia-Ju Bai <baijiaju1990@xxxxxxx>]

According to pcmcia.c, the driver may sleep under a spinlock.
The function call paths are:
ssb_pcmcia_read8 (acquire the spinlock)
  select_core_and_segment
    ssb_pcmcia_switch_segment
      ssb_pcmcia_cfg_write
        pcmcia_write_config_byte
          pcmcia_access_config (drivers/pcmcia/pcmcia_resource.c)
            mutex_lock --> may sleep

ssb_pcmcia_read8 (acquire the spinlock)
  select_core_and_segment
    ssb_pcmcia_switch_segment
      sssb_pcmcia_cfg_read
        pcmcia_read_config_byte
          pcmcia_access_config (drivers/pcmcia/pcmcia_resource.c)
            mutex_lock --> may sleep

A possible fix is to use spinlock instead of mutex lock in 
pcmcia_access_config in drivers/pcmcia/pcmcia_resource.c.

These bugs are found by my static analysis tool and my code review.


Thanks,
Jia-Ju Bai