Revert "panic: Add board ID to panic output"

This reverts commit 4e09c510.

I checked for the usage of this debug helper in AOSP common kernels as
well as vendor kernels (e.g exynos, msm, mediatek, omap, tegra, x86,
x86_64) hosted at https://android.googlesource.com/kernel/

 and I found
out that other than few fairly obsolete Omap trees (for tuna & Glass)
and Exynos tree (for Manta), there is no active user of this debug
helper. So we can safely remove this helper code.

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>