cnss2: Remove improper runtime PM enablement checks

Currently CNSS runtime PM APIs will check runtime PM enablement using
pm_runtime_enabled() by checking for disable_depth which can be changed
at any time. This may cause usage count imbalance since the CNSS API may
skip calling the corresponding runtime PM framework API to increase or
decrease usage count. Remove all these improper checks.

Change-Id: Ibe0802fd8e41bc9ade148d374dc55295736d0c1e
Signed-off-by: Yue Ma <yuem@codeaurora.org>