spi/spi_mpc8xxx: Do not use map_tx_dma to unmap rx_dma
spi/spi_mpc8xxx: Do not use map_tx_dma to unmap rx_dma

This fixes a typo were map_tx_dma is used instead of
map_rx_dma, casing the driver to unmap rx_dma when it
shouldn't.

Signed-off-by: Joakim Tjernlund <28ec1adb181e0f7ff73a9ed1532c061a187559fb@transmode.se>
Acked-by: Anton Vorontsov <1d765a3da7f714ffaadb979466c507aa3415181f@gmail.com>
Signed-off-by: Grant Likely <9069e6f5a2b566e2674a0ba1e2bf39c12c195fad@secretlab.ca>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas