vendorcode/cavium: Supply bdk_pop and bdk_dpop definitions

vendorcode/cavium: Supply bdk_pop and bdk_dpop definitions

This is an issue found by the new builder image and needs to be fixed
before we can upgrade to the new toolchain version:

In function `bdk_dram_get_size_mbytes':
src/vendorcode/cavium/bdk/libbdk-dram/bdk-dram-size.c:198:
undefined reference to `bdk_pop'

In function `bdk_get_num_cores':
/src/vendorcode/cavium/include/bdk/libbdk-hal/bdk-utils.h:164:
undefined reference to `bdk_dpop'

In function `init_octeon3_ddr3_interface':
src/vendorcode/cavium/bdk/libdram/dram-init-ddr3.c:7550:
undefined reference to `bdk_pop'

Change-Id: Ibf71e4556014795bfedceccfe3837dc9deb29ad2
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/c/29851
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>