mips: octeon: Update EBB7304 defconfig

This patch enables the following options for the Octeon EBB7304 EVB:

- PCI & DM_PCI
- DM_SPI_FLASH & SPI flash device support
- SPI & Octeon SPI driver
- GPIO cmd support
- I2C cmd support

Signed-off-by: Stefan Roese <sr@denx.de>