microblaze: Fix MB_MANAGER build with older binutils

microblaze: Fix MB_MANAGER build with older binutils

Commit 88707ebe77e2 ("microblaze: Add custom break vector handler for mb
manager") added the suspend mnemonic to the MB Manager break handler.

GNU as only learned this mnemonic in binutils 2.42. Linux supports
binutils 2.30, where enabling CONFIG_MB_MANAGER fails:

  arch/microblaze/kernel/entry.S:946: Error: unknown opcode "suspend"

The suspend mnemonic is an alias for mbar 24, and both encode as
0xbb020004. Use the underlying instruction, which GNU as 2.30 already
supports.

Fixes: 88707ebe77e2 ("microblaze: Add custom break vector handler for mb manager")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202310310151.UhB396Qs-lkp@intel.com/
Suggested-by: Michal Simek <monstr@monstr.eu>
Cc: stable@vger.kernel.org
Assisted-by: Codex:gpt-5.6-sol
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Link: https://patch.msgid.link/20260813024026.5402-1-kmehltretter@gmail.com
Signed-off-by: Michal Simek <michal.simek@amd.com>