brcmfmac: use jiffies for timeout in btcoex

The btcoex uses a timeout which was in milliseconds and got
converted to jiffies upon using timer api. Instead, convert
it to jiffies and treat it as such further.

Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Reviewed-by: Franky (Zhenhui) Lin <frankyl@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>