ata: remove palmchip pata_bk3710 driver

This device was used only on the davinci dm644x platform that
is now gone, and no references to the device remain in the
kernel.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Marc Zyngier <maz@kernel.org>
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>