[OpenAFS] 1.5.53 and 1.5.54 do no more compile with Linux 2.4

[Axel Reinhold]

While 1.5.52 did well with Linux 2.4 - since the last two versions 1.5.53 and 1.5.54 no more compiling:

openafs-1.5.54/src/afs/LINUX/osi_vnodeops.c: In function 'afs_linux_read':
openafs-1.5.54/src/afs/LINUX/osi_vnodeops.c:97: error: 'struct file' has no member named 'f_mapping'