The QSPI spec allows alt to be any size that is a multiple of the
number of data lines. For example, Micron's N25Q128A uses only a
single alt cycle for all read modes (1, 2, or 4 bits depending on
how many data lines are in use).
Add the functions qspi_master_sclk_pinmap, qspi_master_ssel_pinmap and
qspi_master_data0_pinmap-qspi_master_data3_pinmap to all targets with
qspi support.
The code is written such that access to the data input/output happens word-by-word, and that means unaligned access is fine (though with a performance loss) on Cortex-M3/M4 devices.