mmc: block: avoid multiblock reads for the last sector in SPI mode

On some SD cards over SPI, reading with the multiblock read command the last
sector will leave the card in a bad state.

Remove last sectors from the multiblock reading cmd.

Signed-off-by: Chris Boot <bootc@bootc.net>
Signed-off-by: Clément Péron <peron.clem@gmail.com>
Cc: stable@vger.kernel.org # v4.10+
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>