staging: ccree: refactor HW command FIFO access

The programming of the HW command FIFO in ccree was done via
a set of macros which suffer a few problems:
- Use of macros rather than inline leaves out parameter type
  checking and risks multiple macro parameter evaluation side
  effects.
- Implemented via hand rolled versions of bitfield operations.

This patch refactors the HW command queue access into a set
of inline functions using generic kernel bitfield access
infrastructure, thus resolving the above issues and opening
the way later on to drop the hand rolled bitfield macros
once additional users are dropped in later patches in the
series.

Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>