sparc32,leon: SRMMU MMU Table probe fix

The LEON MMU Model (SRMMU) does not implement MMu Table probing
in hardware, instead it is implemented in software. However the
software implementation does not return the PTE as it should which
always results in INVALID entires and the PROM mappings are not
inherited as they should during startup. The following patch
removes the masking of the PTE.

Signed-off-by: Daniel Hellstrom <daniel@gaisler.com>
Signed-off-by: David S. Miller <davem@davemloft.net>