Blackfin: add os log functions

Part of the mini Blackfin ABI with operating systems is that they can use
0x4f0-0x4f8 to pass log buffers to/from bootloaders.  So add support to
U-Boot for reading the log buffer.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/include/asm-blackfin/blackfin_local.h b/include/asm-blackfin/blackfin_local.h
index e17d8a2..8ec7928 100644
--- a/include/asm-blackfin/blackfin_local.h
+++ b/include/asm-blackfin/blackfin_local.h
@@ -61,6 +61,9 @@
 
 # define bfin_revid() (*pCHIPID >> 28)
 
+extern bool bfin_os_log_check(void);
+extern void bfin_os_log_dump(void);
+
 extern void blackfin_icache_flush_range(const void *, const void *);
 extern void blackfin_dcache_flush_range(const void *, const void *);
 extern void blackfin_icache_dcache_flush_range(const void *, const void *);