Add missing fpu mode to mipsel r1 toolchain

It's present for host and simulator builds.

BUG=none
R=machenbach@chromium.org

Review-Url: https://codereview.chromium.org/1941723002
Cr-Commit-Position: refs/heads/master@{#35932}

gypfiles/toolchain.gypi

@@ -667,6 +667,9 @@
                     'ldflags': ['-mips32r2'],
                   }],
                   ['mips_arch_variant=="r1"', {
+                    'defines': [
+                      'FPU_MODE_FP32',
+                    ],
                     'cflags!': ['-mfp64', '-mfpxx'],
                     'conditions': [
                       [ 'clang==0', {