MIPS: make inclusion of ROM exception vectors configurable

This adds a compile time option to include code for static
exception vectors. Static exception vectors are only needed,
when the U-Boot entry point is equal to the CPU reset exception
vector address. For instance this is the case when U-Boot is
used as ROM in Qemu or booted from parallel NOR flash. When
U-Boot is booted from RAM (e.g. loaded there by SPL), the
exception vectors need to be setup dynamically, which is done
in follow-up commits.

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
diff --git a/arch/mips/mach-ath79/Kconfig b/arch/mips/mach-ath79/Kconfig
index 7d483aa..d982b0f 100644
--- a/arch/mips/mach-ath79/Kconfig
+++ b/arch/mips/mach-ath79/Kconfig
@@ -9,6 +9,7 @@
 	select SUPPORTS_BIG_ENDIAN
 	select SUPPORTS_CPU_MIPS32_R1
 	select SUPPORTS_CPU_MIPS32_R2
+	select ROM_EXCEPTION_VECTORS
 	select MIPS_TUNE_24KC
 	help
 	  This supports QCA/Atheros ar933x family SOCs.
@@ -27,6 +28,7 @@
 	select SUPPORTS_BIG_ENDIAN
 	select SUPPORTS_CPU_MIPS32_R1
 	select SUPPORTS_CPU_MIPS32_R2
+	select ROM_EXCEPTION_VECTORS
 	select MIPS_TUNE_24KC
 	help
 	  This supports QCA/Atheros qca953x family SOCs.