ufs: don't disable_irq() if the IRQ can be shared among devices

When removing the UFS driver, disable_irq() is called and the IRQ is
not enabled again.  Unfortunately, the IRQ is requested with IRQF_SHARED
and it can be shared among several devices.  So disabling the IRQ in
this way is just breaking other devices which are sharing the IRQ.

Change-Id: Icf7fb9ff50de33a2755466be5441d68bc34c0f96
Signed-off-by: Akinobu Mita <mita@fixstars.com>
Cc: Vinayak Holikatti <vinholikatti@gmail.com>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Cc: linux-scsi@vger.kernel.org
Signed-off-by: Santosh Y <santoshsy@gmail.com>
Patch-mainline: linux-scsi@vger.kernel.org @ 07/28/13, 08:10
Signed-off-by: Dolev Raviv <draviv@codeaurora.org>