am335x_evm: enable BTRFS commands

Signed-off-by: Stefan Agner <stefan@agner.ch>
btrfs: use PLATFORM_NO_UNALIGNED to allow unaligned access (avoids data abort)

Signed-off-by: Stefan Agner <stefan@agner.ch>
btrfs: Fix path parsing, don't free root inode when using paths with leading /

Signed-off-by: Stefan Agner <stefan@agner.ch>
btrfs: removed btrfs_mangle_name which limited pathlenghts to 20 characters