treewide: strip useless default n Kconfig lines

Kconfig docs say:
> The default value deliberately defaults to 'n' in order to avoid
> bloating the build.

Apply this rule everywhere, to avoid more cloning of bad examples

Signed-off-by: Tony Butler <spudz76@gmail.com>

target/linux/at91/image/Config.in

@@ -1,10 +1,8 @@
 config AT91_DFBOOT
 	bool "Build dataflashboot loader"
 	depends on TARGET_at91
-	default n
 
 config FLEXIBITY_ROOT
 	bool "Build Flexibity RootFS (with embedded kernel)"
 	depends on TARGET_at91_flexibity
-	default n
 

target/linux/ath79/files/drivers/net/ethernet/atheros/ag71xx/Kconfig

@@ -10,14 +10,12 @@ if AG71XX
 
 config AG71XX_DEBUG
 	bool "Atheros AR71xx built-in ethernet driver debugging"
-	default n
 	help
 	  Atheros AR71xx built-in ethernet driver debugging messages.
 
 config AG71XX_DEBUG_FS
 	bool "Atheros AR71xx built-in ethernet driver debugfs support"
 	depends on DEBUG_FS
-	default n
 	help
 	  Say Y, if you need access to various statistics provided by
 	  the ag71xx driver.

target/linux/generic/files/drivers/mtd/mtdsplit/Kconfig

@@ -12,7 +12,6 @@ config MTD_SPLIT_SQUASHFS_ROOT
 	bool "Squashfs based root partition parser"
 	depends on MTD_SPLIT_SUPPORT
 	select MTD_SPLIT
-	default n
 	help
 	  This provides a parsing function which allows to detect the
 	  offset and size of the unused portion of a rootfs partition

target/linux/generic/files/drivers/platform/mikrotik/Kconfig

@@ -1,6 +1,5 @@
 menuconfig MIKROTIK
 	bool "Platform support for MikroTik RouterBoard virtual devices"
-	default n
 	help
 	  Say Y here to get to see options for the MikroTik RouterBoard platform.
 	  This option alone does not add any kernel code.