riscv: Kconfig: Allow RV32 to build with no MMU

Some RISC-V 32bit cores do not have an MMU, and the kernel should be
able to build for them. This patch enables the RV32 to be built with
no MMU support.

Signed-off-by: Yimin Gu <ustcymgu@gmail.com>
CC: Jesse Taube <Mr.Bossman075@gmail.com>
Tested-by: Waldemar Brodkorb <wbx@openadk.org>
Signed-off-by: Jesse Taube <Mr.Bossman075@gmail.com>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230301002657.352637-3-Mr.Bossman075@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Author: regymm

arch/riscv/Kconfig

@@ -177,8 +177,8 @@ config MMU
 
 config PAGE_OFFSET
 	hex
-	default 0xC0000000 if 32BIT
-	default 0x80000000 if 64BIT && !MMU
+	default 0xC0000000 if 32BIT && MMU
+	default 0x80000000 if !MMU
 	default 0xff60000000000000 if 64BIT
 
 config KASAN_SHADOW_OFFSET
@@ -279,7 +279,6 @@ config ARCH_RV32I
 	select GENERIC_LIB_ASHRDI3
 	select GENERIC_LIB_LSHRDI3
 	select GENERIC_LIB_UCMPDI2
-	select MMU
 
 config ARCH_RV64I
 	bool "RV64I"