ARM: bcm2835: convert to multi-platform

This allows BCM2835 be included in a kernel build that supports multiple
SoCs at once, which is useful for distro kernels.

This change:
* Moves bcm2835's debug-macro.S into ARM's include/debug/, and hooks it
  into the relevant menu.
* Moves bcm2835's Kconfig into its own directory, as seems typical for
  multi-platform conversions.
* Removes bcm2835_soc.h, and moves the content to the files where it was
  used; just one usage per define.
* Deletes some headers and Makefile.boot that aren't needed now that we
  support multi-platform.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index acdddda..a877d51 100644
--- a/arch/arm/Kconfig.debug
+++ b/arch/arm/Kconfig.debug
@@ -89,6 +89,10 @@
 		bool "Kernel low-level debugging on 9263 and 9g45"
 		depends on HAVE_AT91_DBGU1
 
+	config DEBUG_BCM2835
+		bool "Kernel low-level debugging on BCM2835 PL011 UART"
+		depends on ARCH_BCM2835
+
 	config DEBUG_CLPS711X_UART1
 		bool "Kernel low-level debugging messages via UART1"
 		depends on ARCH_CLPS711X
@@ -579,6 +583,7 @@
 
 config DEBUG_LL_INCLUDE
 	string
+	default "debug/bcm2835.S" if DEBUG_BCM2835
 	default "debug/icedcc.S" if DEBUG_ICEDCC
 	default "debug/imx.S" if DEBUG_IMX1_UART || \
 				 DEBUG_IMX25_UART || \