Description: dpll: sanitize possible null pointer dereference in dpll_pin_parent_pin_set()
References:
 https://bugzilla.redhat.com/show_bug.cgi?id=2253986
 https://lore.kernel.org/netdev/20231211083758.1082853-1-jiri@resnulli.us/
Notes:
 carnil> Commit fixes 9d71b54b65b1 ("dpll: netlink: Add DPLL framework
 carnil> base functions") in 6.7-rc1.
Bugs:
upstream: released (6.7-rc6) [65c95f78917ea6fa7ff189a2c19879c4fe161873]
6.1-upstream-stable: N/A "Vulnerable code not present"
5.10-upstream-stable: N/A "Vulnerable code not present"
4.19-upstream-stable: N/A "Vulnerable code not present"
sid: N/A "Vulnerable code not present"
6.1-bookworm-security: N/A "Vulnerable code not present"
5.10-bullseye-security: N/A "Vulnerable code not present"
4.19-buster-security: N/A "Vulnerable code not present"