i2c: rcar: should depend on HAS_DMA

If NO_DMA=y:

    drivers/built-in.o: In function `rcar_i2c_dma_unmap':
    i2c-rcar.c:(.text+0x6f06c6): undefined reference to `bad_dma_ops'
    drivers/built-in.o: In function `rcar_i2c_dma':
    i2c-rcar.c:(.text+0x6f07e2): undefined reference to `bad_dma_ops'
    i2c-rcar.c:(.text+0x6f0838): undefined reference to `bad_dma_ops'

Add a dependency on HAS_DMA to fix this.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>