The DEXCR emulation was recently changed to a 32-bit register, possibly
because it does have a 32-bit read-only view. It is a full 64-bit
SPR though, so use the corresponding 64-bit write functions.
Fixes: fbda88f7abdee ("target/ppc: Fix width of some 32-bit SPRs") Reviewed-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Benjamin Gray <bgray@linux.ibm.com> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>