tests: Add tests to write on chip

This patch adds two tests and initialises page_size in mock chip
chip_W25Q128_V. page_size was not needed for previous tests
(erase and read). page_size only needed to execute writing on chip
with dummyflasher, so it is added here.

BUG=b:181803212
TEST=ninja test

Change-Id: I6f0336613ab16a7e59857006496e3590ddb14d00
Signed-off-by: Anastasia Klimchuk <aklm@chromium.org>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/58357
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>

tests/meson.build

@@ -41,6 +41,7 @@ mocks = [
   '-Wl,--wrap=write',
   '-Wl,--wrap=fopen',
   '-Wl,--wrap=fopen64',
+  '-Wl,--wrap=fdopen',
   '-Wl,--wrap=fwrite',
   '-Wl,--wrap=fflush',
   '-Wl,--wrap=stat',