omap: introduce OMAP_LL_DEBUG_NONE DEBUG_LL config

Zoom2/Zoom3 kind of boards do not use omap uarts for console.
These use external debug board for console.

So these boards should not have "Uncompressing Kernel...."
log put on omap uarts.

By interoducing OMAP_LL_DEBUG_NONE option,
unnecessary writes to omap uarts is avoided.

In future, the DEBUG_LL interface will be enhanced
to use external debug board.
Signed-off-by: Vikram Pandita <vikram.pandita@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/plat-omap/Kconfig

@@ -165,7 +165,7 @@ config OMAP_DM_TIMER
 choice
 	prompt "Low-level debug console UART"
 	depends on ARCH_OMAP
-	default OMAP_LL_DEBUG_UART1
+	default OMAP_LL_DEBUG_NONE
 
 config OMAP_LL_DEBUG_UART1
 	bool "UART1"
@@ -176,6 +176,9 @@ config OMAP_LL_DEBUG_UART2
 config OMAP_LL_DEBUG_UART3
 	bool "UART3"
 
+config OMAP_LL_DEBUG_NONE
+	bool "None"
+
 endchoice
 
 config OMAP_SERIAL_WAKE

arch/arm/plat-omap/include/plat/uncompress.h

@@ -44,8 +44,12 @@ static void putc(int c)
 	uart = (volatile u8 *)(OMAP_UART3_BASE);
 #elif defined(CONFIG_OMAP_LL_DEBUG_UART2)
 	uart = (volatile u8 *)(OMAP_UART2_BASE);
-#else
+#elif defined(CONFIG_OMAP_LL_DEBUG_UART1)
 	uart = (volatile u8 *)(OMAP_UART1_BASE);
+#elif defined(CONFIG_OMAP_LL_DEBUG_NONE)
+	return;
+#else
+	return;
 #endif
 
 #ifdef CONFIG_ARCH_OMAP1