RC: Fix charging LED and LED brightness settings

I know it's not a good practice to have a separate function with only
one line, but for code cleanness I kept setSystemProp.

Change-Id: I7ff0370fa9028504f898dfbb0100316753a5d5b5
Signed-off-by: Gergely Szell (sethyx) <szell@hu.ibm.com>