esp32: Remove traditional "make" capability.

It's now replaced by cmake/idf.py.  But a convenience Makefile is still
provided with traditional targets like "all" and "deploy".
Signed-off-by: Damien George <damien@micropython.org>

ports/esp32/boards/GENERIC/mpconfigboard.mk

-SDKCONFIG += boards/sdkconfig.base

ports/esp32/boards/GENERIC_D2WD/mpconfigboard.mk

-SDKCONFIG += boards/sdkconfig.base
-PART_SRC = partitions-2MiB.csv
-FLASH_SIZE = 2MB
-FLASH_MODE = dio
-FLASH_FREQ = 40m

ports/esp32/boards/GENERIC_OTA/mpconfigboard.mk

-SDKCONFIG += boards/sdkconfig.base
-SDKCONFIG += boards/GENERIC_OTA/sdkconfig.board
-
-PART_SRC = partitions-ota.csv

ports/esp32/boards/GENERIC_SPIRAM/mpconfigboard.mk

-SDKCONFIG += boards/sdkconfig.base
-SDKCONFIG += boards/sdkconfig.spiram

ports/esp32/boards/TINYPICO/mpconfigboard.mk

-FLASH_FREQ = 80m
-
-SDKCONFIG += boards/sdkconfig.base
-SDKCONFIG += boards/sdkconfig.240mhz
-SDKCONFIG += boards/sdkconfig.spiram
-SDKCONFIG += boards/TINYPICO/sdkconfig.board
-
-FROZEN_MANIFEST ?= $(BOARD_DIR)/manifest.py