riscv: Correct SPARSEMEM configuration

There are two issues for RV32,
1) if use FLATMEM, it is useless to enable SPARSEMEM_STATIC.
2) if use SPARSMEM, both SPARSEMEM_VMEMMAP and SPARSEMEM_STATIC is enabled.

Fixes: d95f1a54 ("RISC-V: Implement sparsemem")
Signed-off-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: NPalmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/Kconfig

@@ -93,7 +93,6 @@ config RISCV
 	select PCI_MSI if PCI
 	select RISCV_INTC
 	select RISCV_TIMER if RISCV_SBI
-	select SPARSEMEM_STATIC if 32BIT
 	select SPARSE_IRQ
 	select SYSCTL_EXCEPTION_TRACE
 	select THREAD_INFO_IN_TASK
@@ -154,7 +153,8 @@ config ARCH_FLATMEM_ENABLE
 config ARCH_SPARSEMEM_ENABLE
 	def_bool y
 	depends on MMU
-	select SPARSEMEM_VMEMMAP_ENABLE
+	select SPARSEMEM_STATIC if 32BIT && SPARSMEM
+	select SPARSEMEM_VMEMMAP_ENABLE if 64BIT
 
 config ARCH_SELECT_MEMORY_MODEL
 	def_bool ARCH_SPARSEMEM_ENABLE