brcm80211: fmac: move idle macros to dhd_sdio.c

brcm80211: fmac: move idle macros to dhd_sdio.c

The idle macros are only used by dhd_sdio.c. It's more appropriate
to place them in dhd_sdio.c instead of dhd.h.

Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Arend van Spriel <arend@broadcom.com>
Reviewed-by: Alwin Beukers <alwin@broadcom.com>
Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>