spmi: pmic-arb: rename pa_xx to pmic_arb_xx and other cleanup

This patch cleans up the following.

- Rename the "pa" to "pmic_arb".
- Rename the spmi_pmic_arb *dev to spmi_pmic_arb *pmic_arb.
- Rename the pa_{read,write}_data() functions to
  pmic_arb_{read,write}_data().
- Rename channel to APID.
- Rename the HWIRQ_*() macros to hwirq_to_*().
Signed-off-by: NKiran Gunda <kgunda@codeaurora.org>
Reviewed-by: NStephen Boyd <sboyd@codeaurora.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>