configs: Replace CONFIG_ISW_ENTRY_ADDR with CONFIG_SYS_TEXT_BASE

Since 7e0ed13 ("Convert ARCH_OMAP2PLUS boards' CONFIG_SYS_TEXT_BASE to
Kconfig"), a default SYS_TEXT_BASE was set for all ARCH_OMAP2PLUS devices.
CONFIG_ISW_ENTRY_ADDR is used to set SYS_TEXT_BASE in qspi boot.

Simplify this by directly assigning SYS_TEXT_BASE in the defconfig.

Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
diff --git a/configs/am43xx_evm_qspiboot_defconfig b/configs/am43xx_evm_qspiboot_defconfig
index a56abc9..35a412a 100644
--- a/configs/am43xx_evm_qspiboot_defconfig
+++ b/configs/am43xx_evm_qspiboot_defconfig
@@ -2,7 +2,7 @@
 # CONFIG_SYS_THUMB_BUILD is not set
 CONFIG_ARCH_OMAP2PLUS=y
 CONFIG_AM43XX=y
-CONFIG_ISW_ENTRY_ADDR=0x30000000
+CONFIG_SYS_TEXT_BASE=0x30000000
 CONFIG_SYS_EXTRA_OPTIONS="SERIAL1,CONS_INDEX=1,QSPI,QSPI_BOOT"
 CONFIG_QSPI_BOOT=y
 CONFIG_SYS_CONSOLE_INFO_QUIET=y