staging: unisys: Fix remaining CamelCase global variables in virthba.c

This patch fixes the remaining CamelCase global variables in virthba.c reported
by the checkpatch script:
  MaxBuffLen --> max_buff_len
  VirtHbasOpen --> virthbas_open

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