Use the T_PERST_CLK_US macro, and the fsleep() function instead of
usleep_range().

Link: https://lore.kernel.org/linux-pci/20240102-j7200-pcie-s2r-v7-6-a2f9156da6c3@bootlin.comSigned-off-by: Thomas Richard <thomas.richard@bootlin.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>