spi-nor: intel-spi: Fix broken software sequencing codes

commit 9d63f176 upstream.

There are two bugs in current intel_spi_sw_cycle():

- The 'data byte count' field should be the number of bytes
  transferred minus 1
- SSFSTS_CTL is the offset from ispi->sregs, not ispi->base

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Cyrille Pitchen <cyrille.pitchen@wedev4u.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>