LU-11667 tests: Fix sanity test 317 for 64K PAGE_SIZE OST

LU-11667 tests: Fix sanity test 317 for 64K PAGE_SIZE OST

When create a file, blocks are allocated with PAGE_SIZE aligned,
see function osd_ldiskfs_map_inode_pages(). E.g. for 64K PAGE_SIZE
Arm64 OST server, if create a file with size less than 64K, it
actually allocates 128 blocks each block 512 Bytes.

It needs to adjust the test for 64K PAGE_SIZE OST server.

Test-Parameters: trivial
Test-Parameters: clientarch=aarch64 fstype=ldiskfs testlist=sanity \
env=PTLDEBUG=-1,ONLY=317
Test-Parameters: fstype=ldiskfs testlist=sanity \
env=PTLDEBUG=-1,ONLY=317

Change-Id: Iada701f4f424093e847fc70aa843873b75fe6b06
Signed-off-by: Xinliang Liu <xinliang.liu@linaro.org>
Reviewed-on: https://review.whamcloud.com/45395
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>