[inkplate] Rename component and fix grayscale (#10200)

Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>
Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

tests/components/inkplate/common.yaml

@@ -1,5 +1,5 @@
 i2c:
-  - id: i2c_inkplate6
+  - id: i2c_inkplate
     scl: 16
     sda: 17
 
@@ -7,7 +7,7 @@ esp32:
   cpu_frequency: 240MHz
 
 display:
-  - platform: inkplate6
+  - platform: inkplate
     id: inkplate_display
     greyscale: false
     partial_updating: false