platform: generic: thead: separate implement of T-HEAD c9xx pmu

Separate the implement of T-HEAD c9xx pmu to allow any platform with
c9xx cores can use it.

Signed-off-by: Inochi Amaoto <inochiama@outlook.com>
Reviewed-by: Anup Patel <anup@brainfault.org>

platform/generic/include/thead/c9xx_pmu.h

@@ -0,0 +1,7 @@
+
+#ifndef __RISCV_THEAD_C9XX_PMU_H____
+#define __RISCV_THEAD_C9XX_PMU_H____
+
+void thead_c9xx_register_pmu_device(void);
+
+#endif // __RISCV_THEAD_C9XX_PMU_H____