spmi: pmic-arb: rename spmi_pmic_arb_dev to spmi_pmic_arb

Usually *_dev best used for structures that embed a struct device in
them. spmi_pmic_arb_dev doesn't embed one. It is simply a driver data
structure. Use an appropriate name for it.

Also there are many places in the driver that left shift the bit to
generate a bit mask. Replace it with the BIT() macro.
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>