riscv: mm: Return intended SATP mode for noXlvl options

Change the return value of match_noXlvl() to return the SATP mode that
will be used, rather than the mode being disabled. This enables unified
logic for return value judgement with the function that obtains mmu-type
from the fdt, avoiding extra conversion. This only changes the naming,
with no functional impact.

Signed-off-by: Junhui Liu <junhui.liu@pigmoral.tech>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Nutty Liu <liujingqi@lanxincomputing.com>
Link: https://lore.kernel.org/r/20250722-satp-from-fdt-v1-1-5ba22218fa5f@pigmoral.tech
Signed-off-by: Paul Walmsley <pjw@kernel.org>

Author: pigmoral

arch/riscv/kernel/pi/cmdline_early.c

@@ -41,9 +41,9 @@ static char *get_early_cmdline(uintptr_t dtb_pa)
 static u64 match_noXlvl(char *cmdline)
 {
 	if (strstr(cmdline, "no4lvl"))
-		return SATP_MODE_48;
+		return SATP_MODE_39;
 	else if (strstr(cmdline, "no5lvl"))
-		return SATP_MODE_57;
+		return SATP_MODE_48;
 
 	return 0;
 }

arch/riscv/mm/init.c

@@ -864,9 +864,9 @@ static __init void set_satp_mode(uintptr_t dtb_pa)
 
 	kernel_map.page_offset = PAGE_OFFSET_L5;
 
-	if (satp_mode_cmdline == SATP_MODE_57) {
+	if (satp_mode_cmdline == SATP_MODE_48) {
 		disable_pgtable_l5();
-	} else if (satp_mode_cmdline == SATP_MODE_48) {
+	} else if (satp_mode_cmdline == SATP_MODE_39) {
 		disable_pgtable_l5();
 		disable_pgtable_l4();
 		return;