Bootloader cleanup (UNTESTED!)

- Clean up bootloader asm
- Remove fromflash.c - it's not worth doing in C, do it in ASM
- Clean up linker script
- Force use of symbol inside bootphase2 (otherwise linker
  garbage-collects it)
- Link bootloader with gcc instead of ld

bootrom/ram-reset.s

@@ -9,13 +9,12 @@
 .extern BootROM
 
 .section .startphase2,"ax"
-         .code 32
-         .align 0
 
-.global ramstart
-ramstart:
-    ldr     sp,     .stack_end
-    bl      BootROM
+.arm
 
-	.stack_end:
-	.word _stack_end
+.global ram_start
+ram_start:
+	ldr	sp,     =_stack_end
+	bl	BootROM
+
+	.ltorg