ARM: make decompressor debug output user selectable

Make the decompressor debug output user selectable, otherwise merely
enabling DEBUG_LL causes the decompressor to become board specific,
thereby preventing a multi-platform kernel from booting.  Enabling
DEBUG_LL doesn't cause the kernel itself to become platform specific
unless EARLY_PRINTK is enabled, or one of the debugging routines is
added in a path that results in it being called.
Signed-off-by: NRussell King <rmk+kernel@armlinux.org.uk>

arch/arm/Kconfig.debug

@@ -1757,9 +1757,9 @@ config DEBUG_UART_8250_FLOW_CONTROL
 	default y if ARCH_EBSA110 || DEBUG_FOOTBRIDGE_COM1 || DEBUG_GEMINI || ARCH_RPC
 
 config DEBUG_UNCOMPRESS
-	bool
+	bool "Enable decompressor debugging via DEBUG_LL output"
 	depends on ARCH_MULTIPLATFORM || PLAT_SAMSUNG || ARM_SINGLE_ARMV7M
-	default y if DEBUG_LL && !DEBUG_OMAP2PLUS_UART && \
+	depends on DEBUG_LL && !DEBUG_OMAP2PLUS_UART && \
 		     (!DEBUG_TEGRA_UART || !ZBOOT_ROM) && \
 		     !DEBUG_BRCMSTB_UART
 	help