minitest: add/fix gitignore

Signed-off-by: Alessandro Comodi <acomodi@antmicro.com>

minitests/hamsternz-displayport/.gitignore

@@ -0,0 +1,5 @@
+# Outputs
+display_port*
+
+# Build dirs
+build*

minitests/litex/litepcie/.gitignore

@@ -0,0 +1,7 @@
+# Build data
+build*
+*.fasm
+*.ok
+
+# Riscv toolchain
+riscv*

minitests/litex/nexys_video_sata/.gitignore

@@ -1,7 +1,7 @@
-# Python data
-src
-
 # Build data
 build*
 sata.*
 *.ok
+
+# Riscv toolchain
+riscv*