configs: vyasa-rk3288: Fix SPL_TEXT_BASE

The initial Vyasa-rk3288 TPL implementation is to reuse the
SPL_TEXT_BASE for TPL and SPL as 0x0 and 0xff704000 respectively.

But the below commit implements the reverse way of using TEXT_BASE's
like 0xff704000 for TPL and 0x0 for SPL and which indeed update
the SPL_TEXT_BASE for vyasa-rk3288 board.
"rockchip: Kconfig: enable TPL support for rk3328"
(sha1: 3f47db02)

So, fix by dropping the legacy SPL_TEXT_BASE and it will
reassign 0x0 by default based on Kconfig definition.

Reported-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Kever <Yang&lt;kever.yang@rock-chips.com>