Revert "scsi: ufshcd: Flush exception event before suspend"

This reverts commit de406d12.

In case of a background operations exception, there could be a deadlock:
-000|__switch_to()
-001|context_switch(inline)
-001|__schedule()
-002|schedule()
-003|schedule_timeout()
-004|do_wait_for_common(inline)
-004|__wait_for_common(inline)
-004|wait_for_common()
-005|wait_for_completion()
-006|destroy_work_on_stack(inline)
-006|flush_work()
-007|ufshcd_suspend()
-008|ufshcd_runtime_suspend()
-009|ufshcd_pltfrm_runtime_suspend()
-010|pm_generic_runtime_suspend()
-011|__rpm_callback(inline)
-011|rpm_callback()
-012|rpm_suspend()
-013|rpm_idle()
-014|__pm_runtime_idle()
-015|ufshcd_exception_event_handler()
-016|__read_once_size(inline)
-016|static_key_count(inline)
-016|static_key_false(inline)
-016|trace_workqueue_execute_end(inline)
-016|process_one_work()
-017|__read_once_size(inline)
-017|list_empty(inline)
-017|worker_thread()
-018|kthread()
-019|ret_from_fork(asm)

Exception handler tried to suspend UFS synchronously and suspend tries to
flush the currently running exception handler work which results into
deadlock. Revert this change until we find proper fix for this.

Change-Id: I2b8efdf583d08a276b987914c1037619eb8b25f7
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>