spmi: pmic-arb: return the value instead of passing by pointer

Returning the output value from a function, when it is possible, is the
better and cleaner way than passing it by the pointer. Hence, modify
the ppid_to_apid mapping function to return apid instead of passing
it by a pointer. While at it, pass the ppid as function parameter to
ppid_to_apid mapping function instead of passing the sid and addr.

Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>