boards/launchxl-tms57004: Set LOOPSPERMSEC=0 to avoid build errors

This board does not have a calibrated LOOPSPERMSEC value despite needing
one in order for correct operation. This commits sets the value to 0 so
that CI builds may pass, but users who build this board will see a
warning indicate the steps for calibrating a new value.

Signed-off-by: Matteo Golin <matteo.golin@gmail.com>

Author: linguini1

boards/arm/tms570/launchxl-tms57004/configs/nsh/defconfig

@@ -18,6 +18,7 @@ CONFIG_ARCH_IRQBUTTONS=y
 CONFIG_ARCH_LOWVECTORS=y
 CONFIG_ARCH_STACKDUMP=y
 CONFIG_ARM_TOOLCHAIN_BUILDROOT=y
+CONFIG_BOARD_LOOPSPERMSEC=0
 CONFIG_BUILTIN=y
 CONFIG_FAT_LCNAMES=y
 CONFIG_FAT_LFN=y