err.h: add INIT_ERR_PTR() macro

err.h: add INIT_ERR_PTR() macro

Add INIT_ERR_PTR() macro to initialize static variables with error
pointers. This might be useful for specific case where there is a static
variable initialized to an error condition and then later set to the
real handle once probe finish/completes.

This is to handle compilation problems like:

error: initializer element is not constant

where ERR_PTR() can't be used.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20251031130835.7953-2-ansuelsmth@gmail.com
[bjorn: Added () suffix on macro references]
Signed-off-by: Bjorn Andersson <andersson@kernel.org>