leds-pm8xxx: Pass LED flags from board file

Instead of hard coding the flag into led driver, pass it
from board file.
While at it, re-factor the code to separate led upstream
core data with board specific data.

Change-Id: I9726f8444d422fdbebdbd5d5e0c5beb6288aa5b1
Signed-off-by: Jay Chokshi <jchokshi@codeaurora.org>
[sboyd: only take pm8921 part]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>