WebGLRenderer: Fix PCFSoftShadowMap check.

[Mugen87]

Fixed #32591.

Description

I was wondering why using PCFSoftShadowMap in r182 produces no warning so I checked and realized there is a bug in WebGLShadowMap. The current shadow map type is checked on the wrong object reference.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	355.33 84.47	355.34 84.47	+6 B -3 B
WebGPU	617.29 171.26	617.29 171.26	+0 B +0 B
WebGPU Nodes	615.89 171.01	615.89 171.01	+0 B +0 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

	Before	After	Diff
WebGL	487.5 119.34	487.5 119.33	+6 B -4 B
WebGPU	688.74 187.04	688.74 187.04	+0 B +0 B
WebGPU Nodes	638.58 174.23	638.58 174.23	+0 B +0 B