mb/google/cherry: Pre-initialize PCIe at the bootblock stage

Described in PCIe CEM specification sections 2.2 (PERST# Signal) and
2.2.1 (Initial Power-Up (G3 to S0)). The deassertion of PERST# should be
delayed 100ms (TPVPERL) for the power and clock to become stable.

Instead of asserting PERST# right before PCIe initialization and waiting
for 100ms, which is currently the only function of 'mtk_pcie_pre_init',
so that the extra 100ms delay in ramstage is avoided.

TEST=Build pass and boot up to kernel successfully via SSD on Dojo
board, here is the SSD information in boot log:
 == NVME IDENTIFY CONTROLLER DATA ==
    PCI VID   : 0x15b7
    PCI SSVID : 0x15b7
    SN        : 21517J440114
    MN        : WDC PC SN530 SDBPTPZ-256G-1006
    RAB       : 0x4
    AERL      : 0x7
    SQES      : 0x66
    CQES      : 0x44
    NN        : 0x1
Identified NVMe model WDC PC SN530 SDBPTPZ-256G-1006

BUG=b:178565024
BRANCH=cherry

Signed-off-by: Jianjun Wang <jianjun.wang@mediatek.com>
Change-Id: Id5b9369e6f8599f93415588ea585c952a41c5e7d
Reviewed-on: https://review.coreboot.org/c/coreboot/+/62359
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>

0 files changed, 0 insertions, 0 deletions