package/can-utils: enable build using musl libc

package/can-utils: enable build using musl libc

From commit 20fb6d3288f3c9aac7975e505d9a25f21f64bdf9 this package was
disabled for musl because can-utils used the error() glibc extension
at that time.

Since then, can-utils fixed compilation on musl by replacing this
error() calls with err().
https://github.com/linux-can/can-utils/pull/163/commits/791b6de78673f005e9748983231f7260f6b69e99

This commit disables the musl check.

Signed-off-by: Diego Hurtado de Mendoza <diego.hdmp@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>