Revert "workqueue: proper fix for -O3 optimization"

This reverts commit 19d15abacc3dd173f9b6cf5346ee7152c50b7b3a.
Makefile: adding config variable for Ofast compilation
fix build warnings to compile with linaro -Ofast optimization

Conflicts:
	drivers/power/pm8921-bms-htc.c
	drivers/power/pm8921-charger-htc.c