ltp: vma03 fix the alginment of page size

the offset the param of mmap2() doesn't align the page size, but,
this param allow must be a multiple of the page size as returned
by sysconf(_SC_PAGE_SIZE).meanwhile offset * 4096 must be a
multiple of the system page size, so modify the input param of offset
pgoff = (ULONG_MAX - 1)&(~((pgsz-1)>>12));

Signed-off-by: Chuang Dong <Chuang.Dong@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>