serial: make local functions static
spi: make local functions static
tegra: make local functions static
video: ipu: prevent warnings with W=1

- make local functions static
- remove unused is_interlaced function
common:console: add missing include

search_device is declared in iomux, but console only
had the definition. This prevents a warning.
string.h: add missing prototypes
arch-mx: add missing include

mxs_wait_mask_set and friends need a declaration
of struct mxs_register_32.
common/cmd_elf.c: add missing include
gpio: add missing includes
i2c: add missing include
imx: add missing includes
leds: missing include
lib: bootm: add missing include

since the vxworks weaks are reimplement make
sure their prototypes are visible.
mmc: bcm2835_sdhci: add missing include
net: davince: add missing include
omap3: board.c: add missing include

since this file reimplements board_mmc_init,
make sure its prototype is include.

omap3: add missing include

omap3: add missing prototype for cancel

omap3: board: remove dead code
twister: add missing includes
arm: vectors: provide protypes from vectors.S
bootm: add prototype for arch_preboot_os
elf: add prototype for valid_elf_image