stm32g0: Support DAC

Nothing extra needed to be defined here - this might've just been missed
when adding STM32G0 support. Tested and works well on an STM32G051. Registers
in `stm32/common/dac_common_v1.h` match the STM32G0x1 reference manual.

include/libopencm3/stm32/dac.h

@@ -36,6 +36,8 @@
 #       include <libopencm3/stm32/l1/dac.h>
 #elif defined(STM32L4)
 #       include <libopencm3/stm32/l4/dac.h>
+#elif defined(STM32G0)
+#       include <libopencm3/stm32/g0/dac.h>
 #elif defined(STM32G4)
 #	include <libopencm3/stm32/g4/dac.h>
 #elif defined(STM32H7)

include/libopencm3/stm32/g0/dac.h

@@ -0,0 +1,41 @@
+/** @defgroup dac_defines DAC Defines
+ *
+ * @brief <b>Defined Constants and Types for the STM32G0xx Digital-to-Analog Converter</b>
+ *
+ * @ingroup STM32G0xx_defines
+ *
+ * LGPL License Terms @ref lgpl_license
+ */
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef LIBOPENCM3_DAC_H
+#define LIBOPENCM3_DAC_H
+
+#include <libopencm3/stm32/common/dac_common_v1.h>
+
+/**@{*/
+
+/** @defgroup dac_reg_base DAC register base addresses
+@{*/
+#define DAC1				DAC_BASE
+/**@}*/
+
+/**@}*/
+
+#endif
+