ANDROID: firmware_loader: Add support for customer firmware paths

Currently firmware_class.patch commandline can take a single path for
loading firmwares on custom paths. SoC vendors and oems can have
firmwares in multiple file system paths. So add support for paassing
multiple paths through command line for firmware loader.
Add a getter function to read the class path.

For example - firmware_class.path="/vendor,/vendor/firmware_mnt,
/oem/firmware". firmware_class.path can take upto 10 file system
paths with ',' separation.

Bug: 259298396
Change-Id: I31d1470d7dd0255c7aefd856f3c129bdb4b7f2e8
Signed-off-by: Prasad Sodagudi <quic_psodagud@quicinc.com>
Signed-off-by: Vamsi Krishna Lanka <quic_vamslank@quicinc.com>
(cherry picked from commit ce17e299)