driver: spi: cadence: Add ACPI support

commit 54f2383fed4848ffe5a2402896f6fb5d609cc943 from
git@git.assembla.com:cavium/WindRiver.linux.git

These changes enables to read the configs from ACPI tables as
required for successful probing in ACPI uefi environment.
In case of ACPI disabled/dts based environment, it will continue to
read configs from dts as before.

Signed-off-by: Piyush Malgujar <pmalgujar@marvell.com>
Change-Id: Iee96c2a887ccf4fb18fad8558f12cdca548042df
Reviewed-on: https://sj1git1.cavium.com/c/IP/SW/kernel/linux/+/99918
Reviewed-by: Chandrakala Chavva <cchavva@marvell.com>
Reviewed-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Tested-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Signed-off-by: Ruiqiang Hao <Ruiqiang.Hao@windriver.com>