cavium/bdk: Read DDR freq from memory controller

The BDK config subsystem can't store values in romstage.
Read frequency from DDR memory controller instead from
BDK config.

Fixes memory info showing always 0 MT/s.

Change-Id: Iaee33e57e27ca182f41be923cf950868f66d3638
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/27451
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/vendorcode/cavium/bdk/libbdk-dram/bdk-dram-config.c

@@ -106,7 +106,7 @@ const char* bdk_dram_get_info_string(int node)
     snprintf(info_string, INFO_STRING_LEN,
              " %ld MB, %ld MT/s, %s %s",
              bdk_dram_get_size_mbytes(node),
-             bdk_config_get_int(BDK_CONFIG_DDR_SPEED, node),
+             libdram_get_freq_from_pll(node, 0) / 1000000,
              (__bdk_dram_is_ddr4(node, 0)) ? "DDR4" : "DDR3",
              (__bdk_dram_is_rdimm(node, 0)) ? "RDIMM" : "UDIMM");