Description: gianfar: fix jumbo packets+napi+rx overrun crash
References:
Notes:
 bwh> Introduced in 4.8 by commit 6c389fc931bc "gianfar: fix size of
 bwh> scatter-gathered frames".
 bwh> Driver is not enabled by any Debian official config.
Bugs:
upstream: released (5.12-rc3) [d8861bab48b6c1fc3cdbcab8ff9d1eaea43afe7f]
5.10-upstream-stable:  released (5.10.27) [b8bfda6e08b8a419097eea5a8e57671bc36f9939]
4.19-upstream-stable: released (4.19.184) [9943741c2792a7f1d091aad38f496ed6eb7681c4]
4.9-upstream-stable: released (4.9.298) [2cf34285e6eac396a180762c5504e2911df88c9a]
sid: released (5.10.28-1)
5.10-bullseye-security: N/A "Fixed before branching point"
4.19-buster-security: released (4.19.194-1)
4.9-stretch-security: released (4.9.303-1)