debugfs: Add support to print u32 array in debugfs

Move the code from Xen to debugfs to make the code common
for other users as well.

Accked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Suzuki Poulose <suzuki@in.ibm.com>
[v1: Fixed rebase issues]
[v2: Fixed PPC compile issues]
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>