bsps: Move start files to bsps

This patch is a part of the BSP source reorganization.

Update #3285.

bsps/powerpc/qemuppc/start/start.S

@@ -0,0 +1,52 @@
+#include <rtems/score/cpu.h>
+#include <rtems/powerpc/powerpc.h>
+
+#include <bspopts.h>
+
+	.global bsp_interrupt_stack_start
+	.global bsp_interrupt_stack_end
+	.global _start
+
+	.section .bsp_start_text,"awx",@progbits
+
+_start:
+	lis   %r1,bsp_interrupt_stack_start@h
+	ori   %r1,%r1,bsp_interrupt_stack_start@l
+	/* Make sure stack is properly aligned */
+	li    %r3, CPU_STACK_ALIGNMENT - 1
+	andc  %r1, %r1, %r3
+	/* NULL ptr to back chain */
+	li    %r3, 0
+	stw   %r3, 0(%r1)
+
+	li    %r3,8192
+	mtmsr %r3
+
+	/* Read-only small data */
+	lis %r2, _SDA2_BASE_@h
+	ori %r2, %r2,_SDA2_BASE_@l
+
+	/* Read-write small data */
+	lis %r13, _SDA_BASE_@h
+	ori %r13, %r13,_SDA_BASE_@l
+
+        bl      cmain
+	.size _start, . - _start
+
+	.global __eabi
+__eabi:
+	blr
+	.size __eabi, . - __eabi
+
+	.section ".reset","ax"
+_reset:
+	b _start
+	.size _reset, . - _reset
+
+	/* Start stack area */
+	.section ".bsp_rwextra", "aw", @nobits
+	.align 4
+	.space 4096
+bsp_interrupt_stack_start:
+	.space 32768
+bsp_interrupt_stack_end: