pinctrl: qcom: lpass-lpi: Add missed bitfield.h

Previously the cleanup change dropped the bitfield.h from the
pinctrl-lpass-lpi.h, since it's not used there, but forgot to
re-instantiate it in the C-file, where users are located.

Fix this by adding missed bitfield.h to the C-file.

Fixes: aa9430f8 ("pinctrl: qcom: Add missing header(s)")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>