drm/i915: remove IS_ACTIVE

When trying to bring IS_ACTIVE to linux/kconfig.h I thought it wouldn't
provide much value just encapsulating it in a boolean context. So I also
added the support for handling undefined macros as the IS_ENABLED()
counterpart. However the feedback received from Masahiro Yamada was that
it is too ugly, not providing much value. And just wrapping in a boolean
context is too dumb - we could simply open code it.

As detailed in commit babaab2f

 ("drm/i915: Encapsulate kconfig
constant values inside boolean predicates"), the IS_ACTIVE macro was
added to workaround a compilation warning. However after checking again
our current uses of IS_ACTIVE it turned out there is only
1 case in which it triggers a warning in clang (due
-Wconstant-logical-operand) and 2 in smatch. All the others
can simply use the shorter version, without wrapping it in any macro.

So here I'm dialing all the way back to simply removing the macro. That
single case hit by clang can be changed to make the constant come first,
so it doesn't think it's mask:

	-       if (context && CONFIG_DRM_I915_FENCE_TIMEOUT)
	+       if (CONFIG_DRM_I915_FENCE_TIMEOUT && context)

As talked with Dan Carpenter, that logic will be added in smatch as
well, so it will also stop warning about it.

Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20211005171728.3147094-1-lucas.demarchi@intel.com