Revert "spi: mt7621: Fix an error message in mt7621_spi_probe()"

This reverts commit 269f650a which is
commit 2b2bf6b7faa9010fae10dc7de76627a3fdb525b3 upstream.

dev_err_probe() does not suppot in 4.19.y. So this driver will fail to
build.

```
  CC      drivers/staging/mt7621-spi/spi-mt7621.o
drivers/staging/mt7621-spi/spi-mt7621.c: In function 'mt7621_spi_probe':
drivers/staging/mt7621-spi/spi-mt7621.c:446:24: error: implicit declaration of function 'dev_err_probe'; did you mean 'device_reprobe'? [-Werror=implicit-function-declaration]
  446 |                 return dev_err_probe(&pdev->dev, PTR_ERR(clk),
      |                        ^~~~~~~~~~~~~
      |                        device_reprobe
```

Signed-off-by: Nobuhiro Iwamatsu (CIP) <nobuhiro1.iwamatsu@toshiba.co.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>