RDMA/bnxt_re: Fix return code of bnxt_re_configure_cc

RDMA/bnxt_re: Fix return code of bnxt_re_configure_cc

Driver currently supports modifying GEN0_EXT0 CC parameters
through debugfs hook.

Fixed to return -EOPNOTSUPP instead of -EINVAL in bnxt_re_configure_cc()
when the user tries to modify any other CC parameters.

Fixes: 656dff55da19 ("RDMA/bnxt_re: Congestion control settings using debugfs hook")
Signed-off-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Link: https://patch.msgid.link/20250520035910.1061918-4-kalesh-anakkur.purayil@broadcom.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>