brcmfmac: add support for CYW43012 SDIO chipset

CYW43012 is a 1x1 802.11a/b/g/n Dual-Band HT20, 256-QAM/Turbo QAM. It
is an Ultra Low Power WLAN+BT combo chip.

Reviewed-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Chi-Hsien Lin <chi-hsien.lin@cypress.com>
Signed-off-by: Praveen Babu C <praveen.chandran@cypress.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>