kconfig: syntax cleanup - drop support for "depends/requires/def_boolean"

Remove the following redundant and never or rarely used kconfig syntax:

- "def_boolean" (same as "def_bool")
- "requires" (same as "depends on")
- "depends" (same as "depends on")

This patch contains the code changes and Kconfig updates.
The shipped files are in next patch to let actual codechange stand out.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Cc: Bryan Wu <bryan.wu@analog.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dmitry Torokhov <dtor@mail.ru>
Cc: "John W. Linville" <linville@tuxdriver.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

arch/powerpc/Kconfig.debug

@@ -144,7 +144,7 @@ config BDI_SWITCH
 
 config BOOTX_TEXT
 	bool "Support for early boot text console (BootX or OpenFirmware only)"
-	depends PPC_OF && PPC_MULTIPLATFORM
+	depends on PPC_OF && PPC_MULTIPLATFORM
 	help
 	  Say Y here to see progress messages from the boot firmware in text
 	  mode. Requires either BootX or Open Firmware.
@@ -234,12 +234,12 @@ endchoice
 
 config PPC_EARLY_DEBUG_44x_PHYSLOW
 	hex "Low 32 bits of early debug UART physical address"
-	depends PPC_EARLY_DEBUG_44x
+	depends on PPC_EARLY_DEBUG_44x
 	default "0x40000200"
 
 config PPC_EARLY_DEBUG_44x_PHYSHIGH
 	hex "EPRN of early debug UART physical address"
-	depends PPC_EARLY_DEBUG_44x
+	depends on PPC_EARLY_DEBUG_44x
 	default "0x1"
 
 config PPC_EARLY_DEBUG_CPM_ADDR