mtd: spi-nor-core: Add Cypress manufacturer ID in set_4byte

Cypress chips support SPINOR_OP_EN4B(B7h) to enable 4-byte addressing mode.

Cypress chips support B8h to disable 4-byte addressing mode instead of
SPINOR_OP_EX4B(E9h).

This patch defines new opcode and updates set_4byte() to support
enable/disable 4-byte addressing mode for Cypress chips.

Signed-off-by: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>