kconfig: use bool instead of boolean for type definition attributes

Linux stopped the use of keyword 'boolean' in Kconfig.

Refer to commit 6341e62b212a2541efb0160c470e90bd226d5496 ("kconfig:
use bool instead of boolean for type definition attributes")
in Linux Kernel.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/drivers/spmi/Kconfig b/drivers/spmi/Kconfig
index 8d25b45..ab4878e 100644
--- a/drivers/spmi/Kconfig
+++ b/drivers/spmi/Kconfig
@@ -9,13 +9,13 @@
 	  to connect PMIC devices on various SoCs.
 
 config SPMI_MSM
-	boolean "Support Qualcomm SPMI bus"
+	bool "Support Qualcomm SPMI bus"
 	depends on SPMI
 	---help---
 	  Support SPMI bus implementation found on Qualcomm Snapdragon SoCs.
 
 config SPMI_SANDBOX
-	boolean "Support for Sandbox SPMI bus"
+	bool "Support for Sandbox SPMI bus"
 	depends on SPMI
 	---help---
 	  Demo SPMI bus implementation. Emulates part of PM8916 as single