ARM: UniPhier: update the vendor name of UniPhier in Kconfig

The business for UniPhier Soc family has been transferred from
Panasonic Corporation to Socionext Inc.

Update the SoC select menu in Kconfig.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 54e6f26..5611fac 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -77,7 +77,8 @@
 	  registers, 2=32-bit word registers, etc.
 
 config UNIPHIER_SERIAL
-	bool "UniPhier on-chip UART support"
+	bool "Support for UniPhier on-chip UART"
 	depends on ARCH_UNIPHIER && DM_SERIAL
 	help
-	  Support for the on-chip UARTs on the Panasonic UniPhier platform.
+	  If you have a UniPhier based board and want to use the on-chip
+	  serial ports, say Y to this option. If unsure, say N.