This patch returns the SOC version and revision values from
the 'plat_get_soc_version' and 'plat_get_soc_revision' handlers.

Verified using TFTF SMCCC_ARCH_SOC_ID test.

<snip>
> Executing 'SMCCC_ARCH_SOC_ID test'
  TEST COMPLETE                                                 Passed
SOC Rev = 0x102
SOC Ver = 0x36b0019
<snip>

Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>
Change-Id: Ibd7101619143b74f6f6660732daeac1a8bca3e44