staging: unisys: fix CamelCase global Most_recent_message_jiffies

Fix the CamelCase global variable in visorchipset_main.c:
Most_recent_message_jiffies => most_recent_message_jiffies

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>