vbe: Rename vbe_fixup to vbe_request

The vbe_fixup file handles device tree fixups, but these are called OS
requests in VBE. Rename the file to reflect its wider purpose.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/boot/Makefile b/boot/Makefile
index dd45d78..19d628d 100644
--- a/boot/Makefile
+++ b/boot/Makefile
@@ -47,5 +47,5 @@
 obj-$(CONFIG_SPL_LOAD_FIT) += common_fit.o
 endif
 
-obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_VBE) += vbe.o vbe_fixup.o
+obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_VBE) += vbe.o vbe_request.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_VBE_SIMPLE) += vbe_simple.o