staging: unisys: unneeded NULL check

the NULL check for memregion is not required as it has already been
checked for NULL after kzalloc. so we can reach this part of the code
only if memregion is not NULL.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>