blackfin: convert blackfin board_f and board_r to use generic board init functions

- move blackfin specific cpu init code from blackfin board.c to cpu.c
- remove blackfin specific board init code and invoke generic board_f fron cpu init entry
- rename section name bss_vma to bss_start in order to match the generic board init code
- add a fake relocate_code function to set up the new stack only

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
diff --git a/arch/blackfin/cpu/start.S b/arch/blackfin/cpu/start.S
index 29a7c23..f31abfa 100644
--- a/arch/blackfin/cpu/start.S
+++ b/arch/blackfin/cpu/start.S
@@ -196,8 +196,8 @@
 	 * takes care of clearing things for us.
 	 */
 	serial_early_puts("Zero BSS");
-	r0.l = __bss_vma;
-	r0.h = __bss_vma;
+	r0.l = __bss_start;
+	r0.h = __bss_start;
 	r1 = 0 (x);
 	r2.l = __bss_len;
 	r2.h = __bss_len;
@@ -251,3 +251,13 @@
 #endif
 	rts;
 ENDPROC(_get_pc)
+
+ENTRY(_relocate_code)
+	/* Fake relocate code. Setup the new stack only */
+	sp = r0;
+	fp = sp;
+	r0 = p3;
+	r1.h = 0x2000;
+	r1.l = 0x10;
+	jump.l _board_init_r
+ENDPROC(_relocate_code)