bdev: adjust padding to ensure cache line alignment

There is a custom field ext_io_flags which is not part of upstream spdk_bdev_io.
This means that structure size and fields offsets change and the static assert for
driver_ctx cache alignment requirement fails. This patch adjusts the padding so
that the offset for driver_ctx remain cache aligned.

Signed-off-by: Diwakar Sharma <[email protected]>

Author: dsharma-dc

include/spdk/bdev_module.h

@@ -1122,7 +1122,7 @@ struct spdk_bdev_io {
 		struct spdk_bdev_io_zone_mgmt_params zone_mgmt;
 	} u;
 
-	uint8_t reserved3[40];
+	uint8_t reserved3[32];
 
 	/**
 	 *  Fields that are used internally by the bdev subsystem.  Bdev modules