mtd: spi-nor-core: Clean up macros for Infineon(Cypress) S25 and S28

Some macro definitions used in Infineon(Cypress) S25 and S28 series are
redundant and some have inconsistent prefix. This patch removes
redundant ones and renames some to have same prefix as others.

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