mtd: physmap-core: Fix NULL pointer dereferencing in of_select_probe_type()

mainline inclusion
from mainline-v6.1-rc1
commit 8b740c08
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I664DZ
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8b740c08eb8202817562c358e8d867db0f7d6565
--------------------------------

Coverity complains of a possible NULL dereference:

in of_select_probe_type():
1. returned_null: of_match_device() returns NULL.
2. var_assigned: match = NULL return value from of_match_device()
309	match = of_match_device(of_flash_match, &dev->dev);

3.dereference: Dereferencing the NULL pointer match.
310	probe_type = match->data;
Signed-off-by: NZeng Jingxiang <linuszeng@tencent.com>
Signed-off-by: NMiquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220727060302.1560325-1-zengjx95@gmail.comSigned-off-by: NXiang Yang <xiangyang3@huawei.com>
Reviewed-by: Nyiyang <yiyang13@huawei.com>
Reviewed-by: Nguozihua <guozihua@huawei.com>
Reviewed-by: NGONG, Ruiqi <gongruiqi1@huawei.com>
Reviewed-by: NXiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: NWang Weiyang <wangweiyang2@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/mtd/maps/physmap-core.c

@@ -307,6 +307,9 @@ static const char *of_select_probe_type(struct platform_device *dev)
 	const char *probe_type;
 
 	match = of_match_device(of_flash_match, &dev->dev);
+	if (!match)
+		return NULL;
+
 	probe_type = match->data;
 	if (probe_type)
 		return probe_type;