msm: hsic_sysmon: Add stub release function

This eliminates the kernel warning that appears when the platform
device is removed by placating the device core's check for a
release function. As the platform_device structure is embedded in
the hsic_sysmon struct, this release function does nothing as
hsic_sysmon_delete() will eventually free everything.

CRs-fixed: 366100
Change-Id: Iff358ec43476b0fe288561cadb2aba297335e0bd
Signed-off-by: Jack Pham <jackp@codeaurora.org>