mwifiex: replace spin_lock_irqsave with spin_lock and fix warn_on

mwifiex: replace spin_lock_irqsave with spin_lock and fix warn_on

We see this WARN_ON during PCIe unload:
WARNING: at kernel/smp.c:382 smp_call_function_many+0x66/0x1e1()

This happens because we are doing PCI iounmap operations while
holding spinlock via spin_lock_irqsave(). Holding spinlock this
way causes disabling IRQs and hence PCI iounmap shows warning on
irqs_disabled() check.

Use non-irq variant of spin_lock i.e. spin_lock() instead.

Signed-off-by: Avinash Patil <patila@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>