RDMA/irdma: avoid fortify-string warning in irdma_clr_wqes

RDMA/irdma: avoid fortify-string warning in irdma_clr_wqes

Commit df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3") triggers a
warning for fortified memset():

In function 'fortify_memset_chk',
    inlined from 'irdma_clr_wqes' at drivers/infiniband/hw/irdma/uk.c:103:4:
include/linux/fortify-string.h:493:25: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
  493 |                         __write_overflow_field(p_size_field, size);
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The problem here isthat the inner array only has four 8-byte elements, so
clearing 4096 bytes overflows that. As this structure is part of an outer
array, change the code to pass a pointer to the irdma_qp_quanta instead,
and change the size argument for readability, matching the comment above
it.

Fixes: 551c46edc769 ("RDMA/irdma: Add user/kernel shared libraries")
Link: https://lore.kernel.org/r/20230523111859.2197825-1-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>