Revert #2051 and replace with a better fix (#2261)

* Revert #2051 and add a better fix for TARGET=generic with DYNAMIC_ARCH
fixes #2257 without breaking #2048 again

Author: martin-frbg

kernel/Makefile.L3

@@ -24,9 +24,11 @@ ifeq ($(TARGET), LOONGSON3B)
 USE_TRMM = 1
 endif
 
-ifeq ($(CORE), GENERIC)
+ifneq ($(DYNAMIC_ARCH), 1)
+ifeq ($(TARGET), GENERIC)
 USE_TRMM = 1
 endif
+endif
 
 ifeq ($(CORE), HASWELL)
 USE_TRMM = 1