PCI: j721e: Deassert PERST# after a delay of PCIE_T_PVPERL_MS milliseconds

PCI: j721e: Deassert PERST# after a delay of PCIE_T_PVPERL_MS milliseconds

According to Section 2.2 of the PCI Express Card Electromechanical
Specification (Revision 5.1), in order to ensure that the power and the
reference clock are stable, PERST# has to be deasserted after a delay of
100 milliseconds (TPVPERL).

Currently, it is being assumed that the power is already stable, which
is not necessarily true.

Hence, change the delay to PCIE_T_PVPERL_MS to guarantee that power and
reference clock are stable.

Fixes: f3e25911a430 ("PCI: j721e: Add TI J721E PCIe driver")
Fixes: f96b69713733 ("PCI: j721e: Use T_PERST_CLK_US macro")
Link: https://lore.kernel.org/r/20241104074420.1862932-1-s-vadapalli@ti.com
Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>