hw/arm/exynos4210: Use the Samsung s3c SDHCI controller

hw/arm/exynos4210: Use the Samsung s3c SDHCI controller

The Exynos SoC has specific SDHCI registers. Use the s3c SDHCI
model which handle these specific registers.

This silents the following "SDHC ... not implemented" warnings so
we can focus on the important registers missing:

  $ qemu-system-arm ... -d unimp \
    -append "... root=/dev/mmcblk0 rootfstype=ext4 rw rootwait" \
    -drive file=linux-build-test/rootfs/arm/rootfs-armv5.ext2,if=sd,format=raw
  [...]
  [   25.744858] sdhci: Secure Digital Host Controller Interface driver
  [   25.745862] sdhci: Copyright(c) Pierre Ossman
  [   25.783188] s3c-sdhci 12530000.sdhci: clock source 2: mmc_busclk.2 (12000000 Hz)
  SDHC rd_4b @0x80 not implemented
  SDHC wr_4b @0x80 <- 0x00000020 not implemented
  SDHC wr_4b @0x8c <- 0x00030000 not implemented
  SDHC rd_4b @0x80 not implemented
  SDHC wr_4b @0x80 <- 0xc0004100 not implemented
  SDHC wr_4b @0x84 <- 0x80808080 not implemented
  [   26.013318] mmc0: SDHCI controller on samsung-hsmmc [12530000.sdhci] using ADMA
  [   26.032318] Synopsys Designware Multimedia Card Interface Driver
  [   42.024885] Waiting for root device /dev/mmcblk0...

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Message-id: 20191005154748.21718-5-f4bug@amsat.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>