configs: Remove redundant CONFIG_TEXT_BASE assignments for Renesas defconfigs

configs: Remove redundant CONFIG_TEXT_BASE assignments for Renesas defconfigs

The Renesas board defconfigs explicitly set CONFIG_TEXT_BASE=0x50000000,
however U-Boot's POSITION_INDEPENDENT=y build default already places text
at 0x0. These hardcoded overrides are therefore unnecessary and will be
pruned automatically in upcoming resyncs.

Remove the CONFIG_TEXT_BASE lines from the following defconfigs:
  - hihope_rzg2_defconfig
  - r8a77970_eagle_defconfig
  - r8a77970_v3msk_defconfig
  - r8a77990_ebisu_defconfig
  - r8a77995_draak_defconfig
  - r8a779a0_falcon_defconfig
  - renesas_rzg2l_smarc_defconfig
  - rz2_beacon_defconfig
  - silinux_ek874_defconfig

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Marek Vasut <marek.vasut+renesas@mailbox.org>