LoongArch: Adjust arch/loongarch/Kconfig

1, ACPI, EFI and SMP are mandatories for LoongArch, select them
unconditionally to avoid various build errors for 'make randconfig'.
2, Move the MMU_GATHER_MERGE_VMAS selection to the correct place.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

arch/loongarch/Kconfig

@@ -2,6 +2,7 @@
 config LOONGARCH
 	bool
 	default y
+	select ACPI
 	select ACPI_GENERIC_GSI if ACPI
 	select ACPI_SYSTEM_POWER_STATES_SUPPORT	if ACPI
 	select ARCH_BINFMT_ELF_STATE
@@ -51,6 +52,7 @@ config LOONGARCH
 	select ARCH_WANTS_NO_INSTR
 	select BUILDTIME_TABLE_SORT
 	select COMMON_CLK
+	select EFI
 	select GENERIC_CLOCKEVENTS
 	select GENERIC_CMOS_UPDATE
 	select GENERIC_CPU_AUTOPROBE
@@ -95,6 +97,7 @@ config LOONGARCH
 	select HAVE_VIRT_CPU_ACCOUNTING_GEN if !SMP
 	select IRQ_FORCED_THREADING
 	select IRQ_LOONGARCH_CPU
+	select MMU_GATHER_MERGE_VMAS if MMU
 	select MODULES_USE_ELF_RELA if MODULES
 	select NEED_PER_CPU_EMBED_FIRST_CHUNK
 	select NEED_PER_CPU_PAGE_FIRST_CHUNK
@@ -102,13 +105,13 @@ config LOONGARCH
 	select OF_EARLY_FLATTREE
 	select PERF_USE_VMALLOC
 	select RTC_LIB
+	select SMP
 	select SPARSE_IRQ
 	select SYSCTL_EXCEPTION_TRACE
 	select SWIOTLB
 	select TRACE_IRQFLAGS_SUPPORT
 	select USE_PERCPU_NUMA_NODE_ID
 	select ZONE_DMA32
-	select MMU_GATHER_MERGE_VMAS if MMU
 
 config 32BIT
 	bool