microblaze: syscalls: switch to generic syscalltbl.sh

Many architectures duplicate similar shell scripts.

This commit converts microblaze to use scripts/syscalltbl.sh.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20210301142303.343727-1-masahiroy@kernel.org


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