RDMA/efa: Rename alloc_ucontext comp_mask to supported_caps

RDMA/efa: Rename alloc_ucontext comp_mask to supported_caps

Following discussion [1], rename the comp_mask field in
efa_ibv_alloc_ucontext_cmd to supported_caps to reflect its actual
usage as a capabilities handshake mechanism rather than a standard
comp_mask. Rename related constants and align function and macro names.

[1] https://lore.kernel.org/linux-rdma/20260312120858.GH1448102@nvidia.com/

Signed-off-by: Michael Margolin <mrgolin@amazon.com>
Link: https://patch.msgid.link/20260316180846.30273-1-mrgolin@amazon.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>