tools: add mkeficapsule to .gitignore

mkeficapsule is a build product. Add it to .gitignore

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/tools/.gitignore b/tools/.gitignore
index a021ea9..a88453f 100644
--- a/tools/.gitignore
+++ b/tools/.gitignore
@@ -20,6 +20,7 @@
 /kwboot
 /lib/
 /mips-relocs
+/mkeficapsule
 /mkenvimage
 /mkexynosspl
 /mkimage