arm: mvebu: Remove A38x BOOT_FROM_UART_ALT 0x3f constant

A385 BootROM treats strapping configuration 0x3f as invalid. When booting
fails (e.g. because of invalid configuration) then BootROM fallbacks to
UART booting.

Detecting BootROM fallback to UART booting is implemented in U-Boot since
commit 2fd4284051e3 ("ARM: mach-mvebu: handle fall-back to UART boot").

So there is no need to define BOOT_FROM_UART_ALT constant and special
handling for it anymore, remove it.

This change effectively revers commit f3a88e2ca17a ("arm: mvebu: fix boot
from UART on ClearFog Base").

Signed-off-by: Pali Rohár <pali@kernel.org>
Tested-by: Tony Dinh <mibodhi@gmail.com>
Tested-by: Martin Rowe <martin.p.rowe@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/arch/arm/mach-mvebu/cpu.c b/arch/arm/mach-mvebu/cpu.c
index 8b91e17..b72037d 100644
--- a/arch/arm/mach-mvebu/cpu.c
+++ b/arch/arm/mach-mvebu/cpu.c
@@ -111,9 +111,6 @@
 		return BOOT_DEVICE_MMC1;
 #endif
 	case BOOT_FROM_UART:
-#ifdef BOOT_FROM_UART_ALT
-	case BOOT_FROM_UART_ALT:
-#endif
 		return BOOT_DEVICE_UART;
 #ifdef BOOT_FROM_SATA
 	case BOOT_FROM_SATA:
diff --git a/arch/arm/mach-mvebu/include/mach/soc.h b/arch/arm/mach-mvebu/include/mach/soc.h
index 6edd2e2..4a94632 100644
--- a/arch/arm/mach-mvebu/include/mach/soc.h
+++ b/arch/arm/mach-mvebu/include/mach/soc.h
@@ -164,7 +164,6 @@
 #define BOOT_FROM_SATA		0x22
 #define BOOT_FROM_UART		0x28
 #define BOOT_FROM_SATA_ALT	0x2A
-#define BOOT_FROM_UART_ALT	0x3f
 #define BOOT_FROM_SPI		0x32
 #define BOOT_FROM_MMC		0x30
 #define BOOT_FROM_MMC_ALT	0x31