staging: unisys: fix CamelCase message header variables

Fix the CamelCase variable names:

g_DiagMsgHdr => g_diag_msg_hdr
g_ChipSetMsgHdr => g_chipset_msg_hdr
g_DelDumpMsgHdr => g_del_dump_msg_hdr

Update all references to use the corrected names.

Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>