configure.sh: use 32-byte SPI blocks
configure.sh: use 32-byte SPI blocks

While kernel 3.17 worked fine with 128-byte block writes, on 3.19 programming
would fail.  As suggested on IRC, lowering the block size to 32 bytes makes
it work.

One possible explanation is that in 3.19 the spi-imx driver has DMA support.
However, DMA is only used for block sizes larger than a threshold.  The
threshold is > 32 bytes (half the FIFO size).

vamposdecampos/novena-gpbb-example,vamposdecampos/novena-gpbb-example,vamposdecampos/novena-gpbb-example