Blackfin: uart: move debug buffers into local bss

There's no need for these saved buffers to be global symbols, or in
the data section.  So mark them static to move them into the bss.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/cpu/serial.c

@@ -49,9 +49,9 @@ DECLARE_GLOBAL_DATA_PTR;
 #include "serial.h"
 
 #ifdef CONFIG_DEBUG_SERIAL
-uint16_t cached_lsr[256];
-uint16_t cached_rbr[256];
-size_t cache_count;
+static uint16_t cached_lsr[256];
+static uint16_t cached_rbr[256];
+static size_t cache_count;
 
 /* The LSR is read-to-clear on some parts, so we have to make sure status
  * bits aren't inadvertently lost when doing various tests.  This also
@@ -112,11 +112,6 @@ int serial_init(void)
 	serial_initialize();
 	serial_setbrg();
 	uart_lsr_clear();
-#ifdef CONFIG_DEBUG_SERIAL
-	cache_count = 0;
-	memset(cached_lsr, 0x00, sizeof(cached_lsr));
-	memset(cached_rbr, 0x00, sizeof(cached_rbr));
-#endif
 	return 0;
 }