staging: tidspbridge: add pud code

And fix the following warning for passing an incorrect
variable type.

../tiomap3430.c: In function 'user_va2_pa':
../tiomap3430.c:1555:
    warning: passing argument 1 of 'pmd_offset' from
    incompatible pointer type
arch/arm/include/asm/pgtable-2level.h:156:
    note: expected 'struct pud_t *' but argument is of
    type 'pmdval_t (*)[2]'

While at it, eliminate 'if' nesting to increase readability.

Signed-off-by: Omar Ramirez Luna <omar.ramirez@copitl.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>