mlxsw: reg: Increase Management Cable Info Access Register length

The layout of the register always supported 128 bytes payloads, but the
driver defined the register with a shorter length because it uses a
maximum payload size of 48 bytes. Increase the register's length in
preparation for using 128 bytes payloads.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Link: https://lore.kernel.org/r/ba5c0f631e2cfd61bd21218d0cbfe03fbfe521f9.1690281940.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>