drives/spi_flash: add spi_flash_cmd_write_page_program()

The SPI flashes that support page programming mode had duplicated
the logic for writing in every driver. Add
spi_flash_cmd_write_page_program() and use the common implementation
to reduce code size that comes from duplication. The savings is
~2.5KiB per stage where the spi flash drivers are utilized.

Change-Id: Ie6db03fa8ad33789f1d07a718a769e4ca8bffe1d
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37963
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>

src/drivers/spi/spi_flash_internal.h

@@ -62,6 +62,10 @@ int spi_flash_cmd_erase(const struct spi_flash *flash, u32 offset, size_t len);
 /* Read status register. */
 int spi_flash_cmd_status(const struct spi_flash *flash, u8 *reg);
 
+/* Write to flash utilizing page program semantics. */
+int spi_flash_cmd_write_page_program(const struct spi_flash *flash, u32 offset,
+				size_t len, const void *buf);
+
 /* Manufacturer-specific probe functions */
 int spi_flash_probe_spansion(const struct spi_slave *spi, u8 *idcode,
 			     struct spi_flash *flash);