Add support MIX2S

Author: ivan19871002

README.md

@@ -24,6 +24,7 @@
 | mocha-kk-oss | Mi Pad | Android KK | tegra-19r15.1-android-4.4 | [mocha-kk-oss](https://github.com/MiCode/Xiaomi_Kernel_OpenSource/tree/mocha-kk-oss) |
 | oxygen-n-oss | Mi MAX2 | Android N | LA.UM.5.6.r1-01900-89xx.0 | [oxygen-n-oss](https://github.com/MiCode/Xiaomi_Kernel_OpenSource/tree/oxygen-n-oss) |
 | pisces-kk-oss | Mi 3 China Mobile | Android KK | tegra-17r18-android-4.2 | [pisces-kk-oss](https://github.com/MiCode/Xiaomi_Kernel_OpenSource/tree/pisces-kk-oss) |
+| polaris-o-oss | Mi MIX2S | Android O | LA.UM.6.3.r1_r00455 | [polaris-o-oss](https://github.com/MiCode/Xiaomi_Kernel_OpenSource/tree/polaris-o-oss) |
 | riva-n-oss | Redmi 4A, Redmi 5, Redmi 5A | Android N | LA.UM.5.6.r1-05900-89xx.0 | [riva-n-oss](https://github.com/MiCode/Xiaomi_Kernel_OpenSource/tree/riva-n-oss) |
 | sagit-n-oss | Mi 6, Mi MIX2 | Android N | MSM8998.LA.1.1.r1-00232-STD.PROD-3 | [sagit-n-oss](https://github.com/MiCode/Xiaomi_Kernel_OpenSource/tree/sagit-n-oss) |
 | sagit-o-oss | Mi 6, Mi MIX2 | Android O | LA.UM.6.4.r1-04900-8x98.0 | [sagit-o-oss](https://github.com/MiCode/Xiaomi_Kernel_OpenSource/tree/sagit-o-oss) |