RDMA/irdma: Prevent overflows in memory contiguity checks

RDMA/irdma: Prevent overflows in memory contiguity checks

irdma_check_mem_contiguous() and irdma_check_mr_contiguous() verify that
PBL entries describe physically contiguous memory ranges.

Both functions calculate byte offsets using 32-bit operands. For example,
with 4 KiB pages, pg_size * pg_idx overflows 32-bit arithmetic when
pg_idx reaches 1048576. In the level-2 check, PBLE_PER_PAGE is 512, so
i * pg_size * PBLE_PER_PAGE overflows when i reaches 2048.

These values are reachable in the driver. For MRs, palloc->total_cnt
comes from iwmr->page_cnt, which is calculated by
ib_umem_num_dma_blocks(). The MR size is limited by IRDMA_MAX_MR_SIZE,
so a 4 GiB MR with 4 KiB pages can reach page_cnt of 1048576. PBLE
resources do not exclude this value either: for gen3, the limit is based
on avail_sds * MAX_PBLE_PER_SD, and MAX_PBLE_PER_SD is 0x40000, so 4 SDs
are enough for 1048576 PBLEs.

Cast one operand to u64 before the multiplications so that the offset
calculations are performed in 64-bit arithmetic.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: b48c24c2d710 ("RDMA/irdma: Implement device supported verb APIs")
Signed-off-by: Aleksandrova Alyona <aga@itb.spb.ru>
Link: https://patch.msgid.link/20260624144846.61242-1-aga@itb.spb.ru
Signed-off-by: Leon Romanovsky <leon@kernel.org>