Revert "Bluetooth: hci_qca: Add delay for wcn3990 stability"

This reverts commit cde9dde6.

The frame reassembly errors were root caused to a transient gpio issue.
The missing response was root caused to an issue with properly managing
RFR in the uart driver.  Addressing those root causes occurs outside of
hci_qca and eliminates the need for the 50ms delay, so remove it.

Signed-off-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>