[PATCH] gdth: reduce large on-stack locals

gdth is the fourth-highest stack user (for a single function)
in 2.6.10-rc3-bk-recent (sizes on x86-32).

Reduce stack usage in gdth driver:
reduce ioc_rescan() from 1564 to 52 bytes;
reduce ioc_hdrlist() from 1528 to 24 bytes;
reduce gdth_get_info() from 1076 to 300 bytes;
Signed-off-by: Randy Dunlap <rddunlap@osdl.org>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>