blackfin: Add <asm/clock.h> to numerous drivers

With d6a320d we moved some clock externs out of blackfin_local.h and
into clock.h but now need to include <asm/clock.h> in more drivers to
avoid warnings.

Cc: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Tom Rini <trini@ti.com>
diff --git a/common/cmd_otp.c b/common/cmd_otp.c
index 6f93335..67808aa 100644
--- a/common/cmd_otp.c
+++ b/common/cmd_otp.c
@@ -18,6 +18,7 @@
 #include <command.h>
 
 #include <asm/blackfin.h>
+#include <asm/clock.h>
 #include <asm/mach-common/bits/otp.h>
 
 static const char *otp_strerror(uint32_t err)