msm_serial_hs: manage PM state when callbacks are disabled

When the system is suspended or the system resume process
has not completed, the client's request to enable the resources
may not succeed. In such cases, ensure the resources do get turned
on and handle the subsequent PM callback properly.

Change-Id: I422436a5f9df66a9d1d87a0e16654e6f1f0e2da8
Signed-off-by: Naveen Kaje <nkaje@codeaurora.org>