ath10k: request credit report if flow control enabled on ep

FW credit flow control is enabled for only WMI ctrl
service(CE3) but credit update is requested unconditionally
on all HTC services as part of HTC tx in CE3/CE0/CE4.

This is causing WOW failure as FW is not expecting credit
report request on other end-points(CE0/CE4).

Request credit report only on those endpoints where
credit flow control is enabled.

Testing:
    Tested on WCN3990 HW.
    Tested FW: WLAN.HL.2.0-01192-QCAHLSWMTPLZ-1.

Signed-off-by: Govind Singh <govinds@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>