raiden_debug_spi.c: Enables USB retry for invalid write count

Enables the USB SPI transfer retry mechanism when the error code
USB_SPI_WRITE_COUNT_INVALID is returned. This error code can
indicate a recoverable USB transfer failure.

BUG=b:153887087
BRANCH=none
TEST=Manual testing of ServoMicro and Flashrom when performing
    reads, writes, and verification of the EC firmware on Nami.
TEST=Modified ServoMicro to randomly corrupt USB packets when
    reading the packet length to replicate bad packets and the
    verify recovery is successful.

Change-Id: I9e6b2ccec0b06aab0d6920f1bddf108058e5d6b1
Signed-off-by: Brian J. Nemec <bnemec@chromium.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/41152


Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>