bootloader: move iram_seg 1k up to have better looking idf_monitor output

bootloader: move iram_seg 1k up to have better looking idf_monitor output

When 2nd stage bootloader loads the ROM bootloader, it prints a
message similar to "entry 0x40080xxx", which idf_monitor decodes
(using application ELF file) as one of the reset vectors (xxx is <
400h). This moves the iram_seg of bootloader 1k up to prevent overlap
of bootloader .text and application vectors, making the output look
nicer. There is still a chance that the entry point decodes as some
symbol in application ELF file, but at least it won't have
"Exception" in its name.