cmd: xtrace: Convert to bool

This variable is a boolean, not a string.

Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index c735e81..f4cff0c 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -65,7 +65,7 @@
 	  to complete a command. Usually "> ".
 
 config SYS_XTRACE
-	string "Command execution tracer"
+	bool "Command execution tracer"
 	depends on CMDLINE
 	default y if CMDLINE
 	help
diff --git a/configs/bcm_ns3_defconfig b/configs/bcm_ns3_defconfig
index d060097..5fb82e9 100644
--- a/configs/bcm_ns3_defconfig
+++ b/configs/bcm_ns3_defconfig
@@ -19,7 +19,7 @@
 # CONFIG_DISPLAY_CPUINFO is not set
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="u-boot> "
-CONFIG_SYS_XTRACE="n"
+CONFIG_SYS_XTRACE=n
 CONFIG_CMD_GPT=y
 CONFIG_CMD_GPT_RENAME=y
 CONFIG_CMD_MMC=y
diff --git a/configs/taurus_defconfig b/configs/taurus_defconfig
index 6198159..1f7e342 100644
--- a/configs/taurus_defconfig
+++ b/configs/taurus_defconfig
@@ -44,7 +44,7 @@
 CONFIG_SPL_DM_SPI_FLASH=y
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="U-Boot> "
-CONFIG_SYS_XTRACE="n"
+CONFIG_SYS_XTRACE=n
 # CONFIG_CMD_BDI is not set
 CONFIG_CMD_BOOTZ=y
 # CONFIG_CMD_IMI is not set