riscv: fix VMALLOC_START definition

stable inclusion
from stable-v5.10.216
commit d5cc3498f0791a4cb70d78fee8027c62573ef55e
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9QRO0
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d5cc3498f0791a4cb70d78fee8027c62573ef55e

--------------------------------

[ Upstream commit ac88ff6b9d7dea9f0907c86bdae204dde7d5c0e6 ]

When below config items are set, compiler complained:

--------------------
CONFIG_CRASH_CORE=y
CONFIG_KEXEC_CORE=y
CONFIG_CRASH_DUMP=y
......
-----------------------

-------------------------------------------------------------------
arch/riscv/kernel/crash_core.c: In function 'arch_crash_save_vmcoreinfo':
arch/riscv/kernel/crash_core.c:11:58: warning: format '%lx' expects argument of type 'long unsigned int', but argument 2 has type 'int' [-Wformat=]
11 |         vmcoreinfo_append_str("NUMBER(VMALLOC_START)=0x%lx\n", VMALLOC_START);
   |                                                        ~~^
   |                                                          |
   |                                                          long unsigned int
   |                                                        %x
----------------------------------------------------------------------

This is because on riscv macro VMALLOC_START has different type when
CONFIG_MMU is set or unset.

arch/riscv/include/asm/pgtable.h:
--------------------------------------------------

Changing it to _AC(0, UL) in case CONFIG_MMU=n can fix the warning.

Link: https://lkml.kernel.org/r/ZW7OsX4zQRA3mO4+@MiWiFi-R3L-srv


Signed-off-by: Baoquan He <bhe@redhat.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>	# build-tested
Cc: Eric DeVolder <eric_devolder@yahoo.com>
Cc: Ignat Korchagin <ignat@cloudflare.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: 6065e736f82c ("riscv: Fix TASK_SIZE on 64-bit NOMMU")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Zhao Mengmeng <zhaomengmeng@kylinos.cn>