libxc: remove broken endianess gate on lz4 decompressor

libxc: remove broken endianess gate on lz4 decompressor

The lz4 decompressor had wrongly implemented a gate between
little-endian and big-endian versions of get_unaligned_le{16/32},
which turns out to be broken on all architectures supported by Xen,
because __LITTLE_ENDIAN is not defined. Instead of trying to fix
this, just implement the little-endian version and remove the switch.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Cc: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>