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.

Change-Id: I432eeb0273cac78638440cd00c64cc568ccd68c5
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>
[collinsd: fix merge conflict]
Signed-off-by: David Collins <collinsd@codeaurora.org>