linux-next build error (10)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    aab7ee9f Add linux-next specific files for 20200717
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=123cefcf100000
kernel config:  https://syzkaller.appspot.com/x/.config?x=66b5d44ee3d87c99
dashboard link: https://syzkaller.appspot.com/bug?extid=2fa4c81b0e82fb808f38
compiler:       gcc (GCC) 10.1.0-syz 20200507

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2fa4c81b0e82fb808f38@xxxxxxxxxxxxxxxxxxxxxxxxx

drivers/mfd/mfd-core.c:147:17: error: implicit declaration of function 'of_read_number' [-Werror=implicit-function-declaration]

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