[l1] PWR: fix style for common code

Code added for L1 to support the PWR Control block didn't properly
follow the HACKING_COMMON_DOC guidelines.  The naming was wrong, and
some headers were missing.  This commit has no functional changes, it
only addresses the style and structure problems.

lib/stm32/l1/pwr.c

@@ -0,0 +1,37 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2012 Karl Palsson <karlp@tweak.net.au>
+ *
+ * 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/>.
+ */
+
+#include <libopencm3/stm32/pwr.h>
+
+void pwr_set_vos_scale(vos_scale_t scale)
+{
+	PWR_CR &= ~(PWR_CR_VOS_MASK);
+	switch (scale) {
+	case RANGE1:
+		PWR_CR |= PWR_CR_VOS_RANGE1;
+		break;
+	case RANGE2:
+		PWR_CR |= PWR_CR_VOS_RANGE2;
+		break;
+	case RANGE3:
+		PWR_CR |= PWR_CR_VOS_RANGE3;
+		break;
+	}
+}
+