Fix for build on 5.4.+ kernels

[rogerjames99]

Fix for building on 5.4.+ kernels. SUBDIRS is no longer parsed by kBuild.

[rogerjames99]

Forgot to add this patch as well.
diff --git a/spi-ch341-usb.c b/spi-ch341-usb.c
index f2ef0a2..eb32262 100644
--- a/spi-ch341-usb.c
+++ b/spi-ch341-usb.c
@@ -620,7 +620,7 @@ static int ch341_spi_probe (struct ch341_device* ch341_dev)
ch341_dev->master->num_chipselect = CH341_SPI_MAX_NUM_DEVICES;
ch341_dev->master->mode_bits = SPI_MODE_3 | SPI_LSB_FIRST;
ch341_dev->master->flags = SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX;

• ch341_dev->master->bits_per_word_mask = SPI_BIT_MASK(8);

• ch341_dev->master->bits_per_word_mask = SPI_BPW_MASK(8);
  ch341_dev->master->transfer_one = ch341_spi_transfer_one;
  ch341_dev->master->max_speed_hz = CH341_SPI_MAX_FREQ;
  ch341_dev->master->min_speed_hz = CH341_SPI_MIN_FREQ;

[jtherin]

up!

[Leo-PL]

@gschorcht please cherry-pick 4e3d6e4 - this fixes build on Ubuntu 20.04 and Debian 11.