virgl: fix the value of VIRGL_DEBUG_BGRA_DEST_SWIZZLE

VIRGL_DEBUG_BGRA_DEST_SWIZZLE should use bit 3.  Make some cosmetic
changes as well.

Fixes: a478e56fbd
    virgl: Add debug flag to bypass driconf to enable the BGRA tweaks

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Reviewed-By: Gert Wollny <gert.wollny@collabora.com>
Reviewed-By: Alexandros Frantzis <alexandros.frantzis@collabora.com>

src/gallium/drivers/virgl/virgl_screen.c

 
 int virgl_debug = 0;
 static const struct debug_named_value debug_options[] = {
-   { "verbose", VIRGL_DEBUG_VERBOSE, NULL },
-   { "tgsi", VIRGL_DEBUG_TGSI, NULL },
-   { "emubgra", VIRGL_DEBUG_EMULATE_BGRA, "Enable tweak to emulate BGRA as RGBA on GLES hosts"},
-   { "bgraswz", VIRGL_DEBUG_BGRA_DEST_SWIZZLE, "Enable tweak to swizzle emulated BGRA on GLES hosts" },
+   { "verbose",   VIRGL_DEBUG_VERBOSE,             NULL },
+   { "tgsi",      VIRGL_DEBUG_TGSI,                NULL },
+   { "emubgra",   VIRGL_DEBUG_EMULATE_BGRA,        "Enable tweak to emulate BGRA as RGBA on GLES hosts"},
+   { "bgraswz",   VIRGL_DEBUG_BGRA_DEST_SWIZZLE,   "Enable tweak to swizzle emulated BGRA on GLES hosts" },
    DEBUG_NAMED_VALUE_END
 };
 DEBUG_GET_ONCE_FLAGS_OPTION(virgl_debug, "VIRGL_DEBUG", debug_options, 0)

src/gallium/drivers/virgl/virgl_screen.h

 #include "util/slab.h"
 #include "virgl_winsys.h"
 
-#define VIRGL_DEBUG_VERBOSE 1
-#define VIRGL_DEBUG_TGSI    2
-#define VIRGL_DEBUG_EMULATE_BGRA 4
-#define VIRGL_DEBUG_BGRA_DEST_SWIZZLE 4
+enum virgl_debug_flags {
+   VIRGL_DEBUG_VERBOSE              = 1 << 0,
+   VIRGL_DEBUG_TGSI                 = 1 << 1,
+   VIRGL_DEBUG_EMULATE_BGRA         = 1 << 2,
+   VIRGL_DEBUG_BGRA_DEST_SWIZZLE    = 1 << 3,
+};
 
 extern int virgl_debug;