cnss2: Fix suspend and resume issue for rome on sa415m

There is pci link up fail and cause 100ms timeout and make the delay
resume not match the suspend and resume KPI. This issue is caused by
the wrong operation to up the pci link during resume when no wlan
driver loaded. In current design, the pci link is set as suspend after
cnss initialization, it is only set to resume when wlan driver load,
but in this case, there is no driver loaded, so it not need to up the
pci link.
For the driver loaded case of suspend and resume, the rome can not
enter suspend because the function cnss_pci_set_mhi_state() will always
return error if the macro CONFIG_MHI_BUS not defined, so add one
judgement to make it enter suspend in this case for rome(qca6174).

Change-Id: I6d47a32d549c2f04a51f776acad70067028aaea9
Signed-off-by: Ke Huang <keh@codeaurora.org>