microblaze: Kconfig: SPL dependencies fixup

Enable SPL_LIBCOMMON_SUPPORT and SPL_LIBGENERIC_SUPPORT if CONFIG_SPL=y, in
order to fix the following link failures:
common/spl/spl.o: in function `board_init_r':
common/spl/spl.c:755: undefined reference to `puts'
...
common/spl/spl.o: in function `board_init_r':
common/spl/spl.c:756: undefined reference to `hang'
common/spl/spl.c:740: undefined reference to `memset'

Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Link: https://lore.kernel.org/r/20211130163358.2531677-4-ovidiu.panait@windriver.com


Signed-off-by: Michal Simek <michal.simek@xilinx.com>