smc: rename smc_find_ism_store_rc to reflect broader usage

smc: rename smc_find_ism_store_rc to reflect broader usage

The function smc_find_ism_store_rc() is used to record the reason
why a suitable device (either ISM or RDMA) could not be found.
However, its name suggests it is ISM-specific, which is misleading.

Rename it to better reflect its actual usage.

No functional changes.

Signed-off-by: Dust Li <dust.li@linux.alibaba.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20251023020012.69609-1-dust.li@linux.alibaba.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>