staging: unisys: fix CamelCase parameter msgHdr in controlvm functions

Fix the CamelCase parameter name

msgHdr => msg_hdr

In all of the controlvm functions in visorchipset_main.c. Update all references
to use the corrected name.

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