kconfig: use bool instead of boolean for type definition attributes

Support for keyword 'boolean' will be dropped later on.

No functional change.

Reference: http://lkml.kernel.org/r/cover.1418003065.git.cj@linux.com
Signed-off-by: Christoph Jaeger <cj@linux.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
diff --git a/drivers/isdn/hardware/mISDN/Kconfig b/drivers/isdn/hardware/mISDN/Kconfig
index b8611e3..09df54f 100644
--- a/drivers/isdn/hardware/mISDN/Kconfig
+++ b/drivers/isdn/hardware/mISDN/Kconfig
@@ -24,7 +24,7 @@
 	   * HFC-E1 (E1 interface for 2Mbit ISDN)
 
 config MISDN_HFCMULTI_8xx
-	boolean "Support for XHFC embedded board in HFC multiport driver"
+	bool "Support for XHFC embedded board in HFC multiport driver"
 	depends on MISDN
 	depends on MISDN_HFCMULTI
 	depends on 8xx