vold: Increase MAX_PARTITIONS to 48

This is needed for certain devices with more than thirty two partitions. (eg. htc jewel, ville)

Change-Id: I244f48c576af05b6569c8c40ebeb4ed1bfa53469

Conflicts:
	DirectVolume.h

vold: allow override of MAX_PARTITIONS for devices with > 4 partitions

Change-Id: Iec4de6e7e5ad52a6dfa45952bb19104f500d9c58a

Conflicts:
	Android.mk

Change-Id: I244f48c576af05b6569c8c40ebeb4ed1bfa53469