board: starfive: visionfive2: deprecate mixed-case product ids VF7110a VF7110b

board: starfive: visionfive2: deprecate mixed-case product ids VF7110a VF7110b

Per recent discussion [1] product IDs VF7110A or VF7110B from EEPROM are
sufficient to select for VisionFive 2 1.2a or VisionFive 2 1.3b boards.
There are no VisionFive 2 products with mixed-case product IDs in EERPOM
so factor out the unnecessary select case conditional.

1: https://lore.kernel.org/u-boot/ZQ2PR01MB1307D97D2C9566B8EE443812E6062@ZQ2PR01MB1307.CHNPR01.prod.partner.outlook.cn/

Signed-off-by: E Shattow <e@freeshell.de>
Reported-by: Hal Feng <hal.feng@starfivetech.com>