Revert "vold: mount ext4 with forced SELinux context"

This reverts commit d5f62d4d78ff5b81512f183df3329cc45f39d19e.

Conflicts:
	Ext4.cpp
Revert "vold: force SELinux context only for sdcard"

This reverts commit a1ad0dc72f40e7448a58b802fac57f8938fd4027.

Conflicts:
	Ext4.cpp
Revert "vold: pass selinux context to ext4 mount (remount ro)"

This reverts commit c442d3753d48cedd3cdd51215b93f107d375a02d.