rtc: add Microcrystal RV-8803 driver

Signed-off-by: Michael Walle <michael@walle.cc>
diff --git a/configs/sandbox64_defconfig b/configs/sandbox64_defconfig
index 29a9df8..827b876 100644
--- a/configs/sandbox64_defconfig
+++ b/configs/sandbox64_defconfig
@@ -163,6 +163,7 @@
 CONFIG_DM_RESET=y
 CONFIG_SANDBOX_RESET=y
 CONFIG_DM_RTC=y
+CONFIG_RTC_RV8803=y
 CONFIG_SANDBOX_SERIAL=y
 CONFIG_SMEM=y
 CONFIG_SANDBOX_SMEM=y
diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
index 6894262..61391a7 100644
--- a/configs/sandbox_defconfig
+++ b/configs/sandbox_defconfig
@@ -179,6 +179,7 @@
 CONFIG_DM_RESET=y
 CONFIG_SANDBOX_RESET=y
 CONFIG_DM_RTC=y
+CONFIG_RTC_RV8803=y
 CONFIG_DEBUG_UART_SANDBOX=y
 CONFIG_SANDBOX_SERIAL=y
 CONFIG_SMEM=y