soc: qcom: sysmon-qmi: fix object corruption due to use after free

While executing multimedia tests which include ADSP SSR testing,
below object corruption observed due to use after free condition.
Add mutex lock to fix the issue.

===============================================
BUG kmalloc-1024 (Tainted: G        W  O   ): \
			Poison overwritten
-----------------------------------------------

INFO: 0xffffffc030db0cb0-0xffffffc030db0cba. \
		First byte 0xff instead of 0x6b
INFO: Allocated in qmi_handle_create+0x4c/0x320 \
			age=14486 cpu=4 pid=32505
	alloc_debug_processing+0x138/0x18c
	___slab_alloc.constprop.61+0x4ec/0x5d0
	__slab_alloc.isra.58.constprop.60+0x48/0x74
	kmem_cache_alloc_trace+0xd4/0x25c
	qmi_handle_create+0x4c/0x320
	sysmon_clnt_svc_arrive+0x34/0xe4
	process_one_work+0x234/0x40c
	worker_thread+0x2e0/0x410
	kthread+0xf4/0xfc
	ret_from_fork+0x10/0x40
INFO: Freed in qmi_handle_destroy+0x154/0x16c \
			age=1159 cpu=4 pid=3784
	free_debug_processing+0x290/0x368
	__slab_free+0x74/0x3ac
	kfree+0x21c/0x290
	qmi_handle_destroy+0x154/0x16c
	sysmon_clnt_svc_exit+0x20/0x30
	process_one_work+0x234/0x40c
	worker_thread+0x2e0/0x410
	kthread+0xf4/0xfc
	ret_from_fork+0x10/0x40

CRs-Fixed: 2009777
Change-Id: If3730f5f972424d49d43d552b7fd1a28e4e0b794
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>