[U-Boot] [PATCH v2] ATMEL: switch atmel_mci users to gen_atmel_mci

Hi List,

this is the second iteration of my patches to switch ATMEL tagets using atmel_mci to gen_atmel_mci.

Changes against v1:

- fix warnings during build - don't rename gen_atmel_mci to atmel_mci

Regards Sven