net: Cache hash and flow_id to avoid recalculation

get_rps_cpu() can cache flow_id and hash as both are required by
set_rps_cpu() instead of recalculating them twice.

Signed-off-by: Krishna Kumar <krikku@gmail.com>
Link: https://patch.msgid.link/20250825031005.3674864-3-krikku@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>