env: ubi: KConfig: add CONFIG_ENV_UBI_VOLUME_REDUND

Introduce the KConfig option CONFIG_ENV_UBI_VOLUME_REDUND for defining
the name of the UBI volume used to store the redundant environment.

Signed-off-by: Markus Klotzbuecher <markus.klotzbuecher@kistler.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
Cc: Kyungmin Park <kmpark@infradead.org>

hs: get rid of stm32mp1* build errors
diff --git a/configs/stm32mp15_basic_defconfig b/configs/stm32mp15_basic_defconfig
index 4aa184f..79687d3 100644
--- a/configs/stm32mp15_basic_defconfig
+++ b/configs/stm32mp15_basic_defconfig
@@ -52,6 +52,7 @@
 CONFIG_ENV_EXT4_FILE="/uboot.env"
 CONFIG_ENV_UBI_PART="UBI"
 CONFIG_ENV_UBI_VOLUME="uboot_config"
+CONFIG_ENV_UBI_VOLUME_REDUND="uboot_config_r"
 CONFIG_STM32_ADC=y
 CONFIG_USB_FUNCTION_FASTBOOT=y
 CONFIG_FASTBOOT_BUF_ADDR=0xC0000000