[MIPS] Kconfig: Enable 64BIT_PHYS_ADDR only through select.

The user should not have to have any clue about this setting.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig

@@ -1427,8 +1427,7 @@ config SB1_PASS_2_1_WORKAROUNDS
 	default y
 
 config 64BIT_PHYS_ADDR
-	bool "Support for 64-bit physical address space"
-	depends on (CPU_R4X00 || CPU_R5000 || CPU_RM7000 || CPU_RM9000 || CPU_R10000 || CPU_SB1 || CPU_MIPS32 || CPU_MIPS64) && 32BIT
+	bool
 
 config CPU_HAS_LLSC
 	bool

arch/mips/au1000/Kconfig

@@ -136,6 +136,7 @@ config SOC_AU1200
 
 config SOC_AU1X00
 	bool
+	select 64BIT_PHYS_ADDR
 	select SYS_HAS_CPU_MIPS32_R1
 	select SYS_SUPPORTS_32BIT_KERNEL
 	select SYS_SUPPORTS_APM_EMULATION