RDMA/irdma: Fix irdma_alloc_ucontext_resp padding

RDMA/irdma: Fix irdma_alloc_ucontext_resp padding

A recent commit modified struct irdma_alloc_ucontext_resp by adding a
member with implicit padding in front of it, though this does not change
the offset of the data members other than m68k. Reported by
scripts/check-uapi.sh:

==== ABI differences detected in include/rdma/irdma-abi.h from 1dd7bde2e91c -> HEAD ====
    [C] 'struct irdma_alloc_ucontext_resp' changed:
      type size changed from 704 to 640 (in bits)
      1 data member deletion:
        '__u8 rsvd3[2]', at offset 640 (in bits) at irdma-abi.h:61:1
      1 data member insertion:
        '__u8 revd3[2]', at offset 592 (in bits) at irdma-abi.h:60:1

Change the size back to the previous version, and remove the implicit
padding by making it explicit and matching what x86-64 would do by placing
max_hw_srq_quanta member into a naturally aligned location.

Fixes: 563e1feb5f6e ("RDMA/irdma: Add SRQ support")
Link: https://patch.msgid.link/r/20251208133849.315451-1-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Jacob Moroni <jmoroni@google.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>