Honor component type in Metal matrix helper functions.

Right now, Metal forces types to full precision. The matrix helper
functions previously baked in that assumption by hard-coding "floatX".
Now, they honor the component type; if this->typeName() started
returning "half", our helper functions would be named with "halfX". This
would allow half-precision and full-precision helpers to coexist.

Change-Id: I1679e6e76d2cf3c27fd69c42a92fb24bff6b69ec
Bug: skia:12339
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/439396
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
4 files changed