cuda: fix reset-all and power-off words

There is a long-standing bug in the CUDA implementation of the reset-all and
power-off words whereby an extra byte is written after the CUDA_RESET_SYSTEM
and CUDA_POWERDOWN commands.

This extra byte used to be ignored in QEMU until commits 017da0b568 ("cuda:
port POWERDOWN command to new framework") and 54e894442e ("cuda: port
RESET_SYSTEM command to new framework") added a check which rejects the
command if the command length is incorrect.

Fix the outgoing command length to remove the extra byte which allows the
reset-all and power-off words to work in QEMU once again.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Hervé Poussineau <hpoussin@reactos.org>
Fixes: qemu#624

drivers/cuda.c

@@ -177,7 +177,7 @@ static cuda_t *main_cuda;
 static void
 ppc32_reset_all(void)
 {
-        uint8_t cmdbuf[2], obuf[64];
+        uint8_t cmdbuf[1], obuf[64];
 
         cmdbuf[0] = CUDA_RESET_SYSTEM;
         cuda_request(main_cuda, CUDA_PACKET, cmdbuf, sizeof(cmdbuf), obuf);
@@ -186,7 +186,7 @@ ppc32_reset_all(void)
 static void
 ppc32_poweroff(void)
 {
-        uint8_t cmdbuf[2], obuf[64];
+        uint8_t cmdbuf[1], obuf[64];
 
         cmdbuf[0] = CUDA_POWERDOWN;
         cuda_request(main_cuda, CUDA_PACKET, cmdbuf, sizeof(cmdbuf), obuf);