nvme: fix reversed loop condition in cmd_readwrite

It looks like the intent was to exit the loop if a command failed, but
the current code would actually continue looping in that case.

Signed-off-by: Daniel Verkamp <daniel@drv.nu>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
diff --git a/src/hw/nvme.c b/src/hw/nvme.c
index c194f9f..97b05cb 100644
--- a/src/hw/nvme.c
+++ b/src/hw/nvme.c
@@ -571,7 +571,7 @@
     u16 const max_blocks = NVME_PAGE_SIZE / ns->block_size;
     u16 i;
 
-    for (i = 0; i < op->count || res != DISK_RET_SUCCESS;) {
+    for (i = 0; i < op->count && res == DISK_RET_SUCCESS;) {
         u16 blocks_remaining = op->count - i;
         u16 blocks = blocks_remaining < max_blocks ? blocks_remaining
                                                    : max_blocks;