From: Juliana Rodrigueiro <redacted>
Date: Wed, 31 Jul 2019 15:17:23 +0200

Since linux 4.9 it is not possible to use buffers on the stack for DMA transfers.

During usb probe the driver crashes with "transfer buffer is on stack" message.

This fix k-allocates a buffer to be used on "read_reg_atomic", which is a macro
that calls "usb_control_msg" under the hood.

Kernel 4.19 backtrace:

 ...

Signed-off-by: Juliana Rodrigueiro <redacted>

Applied.