MIPS: boot: Provide more uImage options

Allow more compression algorithms as well as uncompressed uImage.bin
to be generated. An uncompressed image might be useful to rule out
problems in the decompression code in the bootloader or even speed
up the boot process at the expense of a bigger uImage file.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9271/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>