gowin: Add missing .gitignore entries

techlibs/gowin/.gitignore

diff --git a/techlibs/gowin/.gitignore b/techlibs/gowin/.gitignore
new file mode 100644
index 0000000..d6c48e9
--- /dev/null
+++ b/techlibs/gowin/.gitignore
@@ -0,0 +1,2 @@
+brams_init.mk
+bram_init_*.vh