staging: dgnc: Fix Kconfig help header and text

Replace Kconfig help header and text to match other modules. Issue found
by checkpatch.

Spacing adjusted to match Documentation/process/coding-style.rst. Issue
reported by rdunlap@infradead.org.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Sehro Rautenkranz <sehro@sehro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/dgnc/Kconfig

 config DGNC
-       tristate "Digi Neo and Classic PCI Products"
-       default n
-       depends on TTY && PCI
-       ---help---
-       Driver for the Digi International Neo and Classic PCI based product line.
+	tristate "Digi Neo and Classic PCI Products"
+	default n
+	depends on TTY && PCI
+	help
+	  Say Y here to enable support for the Digi International Neo and
+	  Classic PCI based product line.
+
+	  To compile this driver as a module, say M here: the module will be
+	  called dgnc