RDMA/rxe: Remove 32-bit architecture support

Major linux distibutions have phased out support for 32-bit machines. Since
rxe is primarily used for development and testing, the benefit of
maintaining 32-bit support is minimal. This change simplifies ATOMIC WRITE
implementations and improves maintainability of the driver.

Signed-off-by: Daisuke Matsuda <matsuda-daisuke@fujitsu.com>
Link: https://patch.msgid.link/20250421025101.3588139-1-matsuda-daisuke@fujitsu.com


Signed-off-by: Leon Romanovsky <leon@kernel.org>