net/hsr: update outdated comments

net/hsr: update outdated comments

The function hsr_rcv() was renamed hsr_handle_frame() and moved to
net/hsr/hsr_slave.c by commit 81ba6afd6e64 ("net/hsr: Switch from
dev_add_pack() to netdev_rx_handler_register()").

Update all remaining references in the comments accordingly.

Signed-off-by: Kexin Sun <kexinsun@smail.nju.edu.cn>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260225145159.2953-1-kexinsun@smail.nju.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>