Convert CONFIG_SYS_CBSIZE to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_CBSIZE

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index b50e53e..06ec810 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -75,6 +75,15 @@
 	int "Maximum number arguments accepted by commands"
 	default 16
 
+config SYS_CBSIZE
+	int "Console input buffer size"
+	default 2048 if ARCH_TEGRA || ARCH_VERSAL || ARCH_ZYNQ || ARCH_ZYNQMP || \
+		RCAR_GEN3 || TARGET_SOCFPGA_SOC64
+	default 512 if ARCH_MX5 || ARCH_MX6 || ARCH_MX7 || FSL_LSCH2 || \
+		FSL_LSCH3 || X86
+	default 256 if M68K || PPC
+	default 1024
+
 config SYS_PBSIZE
 	int "Buffer size for console output"
 	default 1044