ANDROID: GKI: Fix CRC signature for possible_net_t

In commit 4cfecb7f ("net: treat possible_net_t net pointer as an RCU
one and add read_pnet_rcu()"), the possible_net_t structure had a
pointer changed to add the __rcu marking to it.  This confuses the CRC
generation, while the binary structure did not change at all.  Fix this
up by putting in the __GENKSYMS__ build fix.

Fixes: 4cfecb7f ("net: treat possible_net_t net pointer as an RCU one and add read_pnet_rcu()")
Change-Id: I9c1ed4da341730d1e4ee1677986876b7e36f33e4
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>