bsp/edb7312: Improve output char

The output char function used by printk() is now independent of the
console driver initialization.

c/src/lib/libbsp/arm/edb7312/console/uart.c

@@ -101,27 +101,36 @@ int uart_poll_read(int minor)
     return c;
 }
 
+static ssize_t uart_do_write(
+    volatile uint32_t *uartdr,
+    const char *buf,
+    size_t len,
+    volatile uint32_t *sysflg
+)
+{
+    size_t i;
+
+    for (i = 0; i < len; i++) {
+        /* Wait for fifo to have room */
+        while ((*sysflg & EP7312_UART_UTXFF1) != 0) {
+            continue;
+        }
+
+        *uartdr = buf[i];
+    }
+
+    return len;
+}
+
 static ssize_t uart_write(int minor, const char *buf, size_t len)
 {
     volatile uint32_t   *data_reg;
     volatile uint32_t   *ctrl_reg2;
-    size_t i;
-    char c;
 
     data_reg  = (uint32_t *)Console_Port_Tbl[minor]->ulDataPort;
     ctrl_reg2 = (uint32_t *)Console_Port_Tbl[minor]->ulCtrlPort2;
 
-    for (i = 0; i < len; i++) {
-        /* Wait for fifo to have room */
-        while ((*ctrl_reg2 & EP7312_UART_UTXFF1) != 0) {
-            continue;
-        }
-
-        c = (char) buf[i];
-        *data_reg = c;
-    }
-
-    return len;
+    return uart_do_write(data_reg, buf, len, ctrl_reg2);
 }
 
 static void uart_init(int minor)
@@ -147,7 +156,7 @@ static void uart_init(int minor)
  */
 static void _BSP_null_char(char c)
 {
-  uart_write_polled(0, c);
+  uart_do_write(EP7312_UARTDR1, &c, 1, EP7312_SYSFLG1);
 }
 
 static int _BSP_get_char(void)