exynos4210: workaround UBSAN compilation error

gcc 5.4.0-6ubuntu1~16.04.5 build with UBSAN enabled error:

  CC      hw/display/exynos4210_fimd.o
/home/petmay01/linaro/qemu-for-merges/hw/display/exynos4210_fimd.c: In
function ‘fimd_get_buffer_id’:
/home/petmay01/linaro/qemu-for-merges/hw/display/exynos4210_fimd.c:1105:5:
error: case label does not reduce to an integer constant
     case FIMD_WINCON_BUF2_STAT:

Because FIMD_WINCON_BUF2_STAT case contains an integer
overflow, use U suffix to get the unsigned type.
Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180116151152.4040-2-marcandre.lureau@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/display/exynos4210_fimd.c

@@ -98,7 +98,7 @@
 #define FIMD_WINCON_BUFSTATUS       ((1 << 21) | (1 << 31))
 #define FIMD_WINCON_BUF0_STAT       ((0 << 21) | (0 << 31))
 #define FIMD_WINCON_BUF1_STAT       ((1 << 21) | (0 << 31))
-#define FIMD_WINCON_BUF2_STAT       ((0 << 21) | (1 << 31))
+#define FIMD_WINCON_BUF2_STAT       ((0 << 21) | (1U << 31))
 #define FIMD_WINCON_BUFSELECT       ((1 << 20) | (1 << 30))
 #define FIMD_WINCON_BUF0_SEL        ((0 << 20) | (0 << 30))
 #define FIMD_WINCON_BUF1_SEL        ((1 << 20) | (0 << 30))