drivers: QMSI PWM: simplify driver reentrancy code using IS_ENABLED macro

This is one the series patches that simplifies the driver code by
using the IS_ENABLED macro. This removes the need of the const
variable and the wrapper functions on semaphore APIs.

Jira: ZEP-1251

Change-Id: Ic2df5d04966d2a066478ca3e119f76d24fc4dfb3
Signed-off-by: Kuo-Lang Tseng <kuo-lang.tseng@intel.com>