flashrom: Drop read_flash_to_file() usage

Aspire towards a goal of making cli_classic more of just
a user of libflashrom than having quasi-parallel paths in
flashrom.c

This converts remaining read_flash_to_file() usage to the
do_read() provider wrapper around libflashrom.

BUG=b:208132085
TEST=`
sudo ./flashrom -p ft2232_spi:type=232H,divisor=1000 -f -r out -c W25X05
Flashrom output:

No EEPROM/flash device found.
Force read (-f -r -c) requested, pretending the chip is there:
Assuming Winbond flash chip "W25X05" (64 kB, SPI) on ft2232_spi.
Please note that forced reads most likely contain garbage.
Block protection could not be disabled!
Reading flash... done.
Data read:

xxd out-1khz
00000000: 0000 07ff ffff e000 0000 7fff fffe 0000  ................
00000010: 0007 ffff ffe0 0000 007f ffff fe00 0000  ................
00000020: 07ff ffff e000 0000 7fff fffe 0000 0007  ................
00000030: ffff ffe0 0000 007f ffff fe00 0000 0fff  ................
xxd out-100khz
00000000: b6db 6db6 db6d b6db 6db6 db6d b6db 6db6  ..m..m..m..m..m.
00000010: db6d b6db 6db6 db6d b6db 6db6 db6d b6db  .m..m..m..m..m..
00000020: 6db6 db6d b6db 6db6 db24 9249 2492 4924  m..m..m..$.I$.I$
00000030: 9249 2492 4924 9249 2492 4924 9249 2492  .I$.I$.I$.I$.I$.
`

Change-Id: I4b690b688acf9d5deb46e8642a252a2132ea8c73
Signed-off-by: Edward O'Callaghan <quasisec@google.com>
Tested-by: Nikolai Artemiev <nartemiev@google.com>
---
M cli_classic.c
M flashrom.c
M include/flash.h
3 files changed, 2 insertions(+), 43 deletions(-)