target/ppc: Replace hard coded constants in ppc_jumbo_xlate()

target/ppc: Replace hard coded constants in ppc_jumbo_xlate()

The "2" in booke206_update_mas_tlb_miss() call corresponds to
MMU_INST_FETCH which is the value of access_type in this branch;
mmubooke206_esr() only checks for MMU_DATA_STORE and it's called from
code access so using MMU_DATA_LOAD here seems wrong so replace it with
access_type here as well that yields the same result. This also makes
these calls the same as the data access branch further down.

Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>