Merged in david_s5/nuttx/upstream_revert_265af481 (pull request #194)

Revert "STM32 serial: Make input hardware flow-control work with RX DMA.  From Jussi Kivilinna"

HSI should not be turned off

This reverts commit 4e051c05.

This change broke the STM32 seril driver.

HSI should not be turned off

STM32F4 does not have the requierment that the HSI be on for FLASH erase/write operations

packed_struct replaced by begin_packed_struct and end_packed_struct

NxWM configurations.  If using a 7-bit character set, then the cursor character cannot be 137 (graphic block).  Use 95 (underscore) instead.

STM32F428i-DISCO:  Change NxWM cursor character from 137 (graphics block) to 95 (underscore).  NxWM is configured to use a 7-bit character set so 137 is not a valid character code.

SAMV7 Ethernet: Fix a compiler error introduced with commit 7467329a