spl: atf: Fix invalid bl32 pc when bl32 is absent

'bl2_to_bl31_params->bl32_ep_info' is Null and '&bl2_to_bl31_params->bl32_ep_info->pc'
is 0x8 when bl32 is absent. That means the pc value is determined by u-boot-spl.bin.
The 0x8 offset of u-boot-spl.bin is the value of '_TEXT_BASE', i.e. CONFIG_SPL_TEXT_BASE.

So far, only rk3576 without bl32 would trigger this issue as DRAM base is 0x40000000.

Let's init bl32_{ep,image}_info even bl32 is absent.

Signed-off-by: Joseph Chen <chenjh@rock-chips.com>
Change-Id: Ic928301baee1c7941f0befd7a89aa74dcbd88cb2