MIPS: Set defconfig target to a generic system for 32r2el

The default system type should be a MIPS generic kernel. In order to
include some level of board support, select a 32r2el generic defconfig
by default. The alternative would be to use "generic_defconfig" but
rather unintuitvely that is a bare bones configuration with no platform
support so is not usable in practice.

Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14715/


Signed-off-by: James Hogan <jhogan@kernel.org>