brcmfmac: CR4 takes precedence over CM3 in brcmf_chip_enter_download()

In the enter and exit download sequence the chip core info was checked
for presence of CM3 ARM core. If found it would enter download state for
the CM3. However, on devices that have a CM3 and CR4 this is not correct
and the CR4 should be used to enter download state. This patch changes
the ARM core lookup giving CR4 precedence.

Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>