microblaze: Make extended addressing support default

Axi qspi controller supports 32-bit & 24-bit addressing modes
for micron, macronix & spansion flash parts. But for winbond
flashes it only supports 24-bit addressing mode.
Enable CONFIG_SPI_FLASH_BAR to use extended addressing mode
to make 32-bit addressing mode work on all flashes.

Signed-off-by: T Karthik Reddy <t.karthik.reddy@xilinx.com>
Acked-by: Ashok Reddy Soma <ashok.reddy.soma@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/f3864966c8ddd766a1702ad61b0e008a1f57462f.1665565423.git.michal.simek@amd.com