rmnet_shs: Remove local_bh_disable in oom handler

Low memory handler in shs is in atomic context so prevent
the disabling of bottom halves.

Change-Id: I0eae18f8876edddd964346fee5b6b39af952d6fa
Acked-by: Raul Martinez <mraul@qti.qualcomm.com>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>