st/vdpau: Include u_format.h for util_format_description.

st/vdpau: Include u_format.h for util_format_description.

Fix build error.

  CC     device.lo
device.c: In function 'vlVdpDefaultSamplerViewTemplate':
device.c:251:4: error: implicit declaration of function 'util_format_description' [-Werror=implicit-function-declaration]
device.c:251:9: warning: assignment makes pointer from integer without a cast [enabled by default]
device.c:252:12: error: dereferencing pointer to incomplete type
device.c:252:28: error: 'UTIL_FORMAT_SWIZZLE_0' undeclared (first use in this function)
device.c:252:28: note: each undeclared identifier is reported only once for each function it appears in
device.c:254:12: error: dereferencing pointer to incomplete type
device.c:256:12: error: dereferencing pointer to incomplete type
device.c:258:12: error: dereferencing pointer to incomplete type

Signed-off-by: Vinson Lee <vlee@freedesktop.org>