In commit 513b20ff the SPI API was changed to
power up an configure the SPI bus on spi_acquire(). Sadly, the lpc2387 SPI
apparently needs to be reconfigured after each power up. This commit moves
the initialization code required after each power up from spi_init() to
spi_acquire().

Fixes misleading .data usage in size output because the .vectors section
is now properly marked as read-only in the ELF file.

vectors and flashsec memory segments will not be considered for orphan
sections if rx is only given for the rom segment.