staging: mt7621-pci: change value for 'PERST_DELAY_MS'

Value of 'PERST_DELAY_MS' is too high and it is ok just
to set up to 100 ms. Update also define name from
'PERST_DELAY_US' into 'PERST_DELAY_MS'

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20200313200913.24321-3-sergio.paracuellos@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>