usb: storage: set pm_suspend_ignore_children to true

The USB UICC devices have storage interface along with smart card
interface. As these devices will be always present, scsi auto-suspend is
enabled by default for UICC card. If we try to remove the UICC card when
USB is in suspended state, scsi block layes tries to resume its parent
which returns EBUSY and it is blocked to process any synchronus request,
scsi remove host is stuck.

As device is already removed, it is safe to set pm_suspend_ignore_children
in scsi remove host so that block layer does not resume parent and fails
synchronus requests queued to it.

CRs-fixed: 659306
Change-Id: I34dff048362303c3565bb4b15c04a7f78b381f56
Signed-off-by: Tarun Gupta <tarung@codeaurora.org>