boot/optee-os: rewrap Config.in help text to fix check-package warning

Fixes:

boot/optee-os/Config.in:140: help text: <tab><2 spaces><62 chars> (http://nightly.buildroot.org/#writing-rules-config-in)

which is a warning that was introduced by commit
46306d135e5aab14073eece713d38e8c827c58ae ("boot/optee-os: add
out-of-source OPTEE-OS device tree support").

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

boot/optee-os/Config.in

@@ -134,12 +134,13 @@ config BR2_TARGET_OPTEE_OS_CUSTOM_DTS_PATH
 	string "Device Tree Source file paths"
 	help
 	  Space-separated list of paths to device tree source files
-	  that will be copied to core/arch/arm/dts/ before starting the
-	  build.
+	  that will be copied to core/arch/arm/dts/ before starting
+	  the build.
 
-	  To use this device tree source file, the OP-TEE OS configuration
-	  must refer to it with the CFG_EMBED_DTB_SOURCE_FILE option and
-	  no platform flavor needs to be specified.
+	  To use this device tree source file, the OP-TEE OS
+	  configuration must refer to it with the
+	  CFG_EMBED_DTB_SOURCE_FILE option and no platform flavor
+	  needs to be specified.
 
 config BR2_TARGET_OPTEE_OS_ADDITIONAL_VARIABLES
 	string "Additional build variables"