LU-6142 fld: remove function typedefs

LU-6142 fld: remove function typedefs

typedefs a generally discouraged in upstream linux.
fld_hash_func_t and fld_scan_func_t are only used
once immediately after the definition, so having them
doesn't help readability or maintainability at all.

So remove them.

Test-Parameters: trivial
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: I37288238f375d5673b7cb8d68d30102f43e44107
Reviewed-on: https://review.whamcloud.com/37740
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>