[Bug] Revert Assymmetrical Split Encoder support (#12090) (#15311)

* Revert "fix broken macro in transport.h (#15239)"

This reverts commit 06f18e22d9.

* Revert "Rework encoders to enable asymmetric split keyboards (#12090)"

This reverts commit 32215d5bff.

quantum/encoder/tests/rules.mk

@@ -1,13 +0,0 @@
-encoder_DEFS := -DENCODER_MOCK_SINGLE
-
-encoder_SRC := \
-	$(QUANTUM_PATH)/encoder/tests/mock.c \
-	$(QUANTUM_PATH)/encoder/tests/encoder_tests.cpp \
-	$(QUANTUM_PATH)/encoder.c
-
-encoder_split_DEFS := -DENCODER_MOCK_SPLIT
-
-encoder_split_SRC := \
-	$(QUANTUM_PATH)/encoder/tests/mock_split.c \
-	$(QUANTUM_PATH)/encoder/tests/encoder_tests_split.cpp \
-	$(QUANTUM_PATH)/encoder.c