staging: hikey9xx: hi6421-spmi-pmic: cleanup IRQ handling code

staging: hikey9xx: hi6421-spmi-pmic: cleanup IRQ handling code

- Use BIT() and GENMASK();
- Remove duplicated mask definitions;
- Simplify the code under IRQ handler;
- Add a few extra blank lines to make easier to see
  spin_lock/spin_unlock;
- Remove debug code;
- Fix a few minor coding style issues.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/f9fcb184e7cbe8701298085df76d5d9fd285b2c5.1611949675.git.mchehab+huawei@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>