Fix cores failing to download

[ArturBieniek4]

Three of the cores in here currently fail to download:

ERROR: Failed to fetch 'pulp-platform.org::apb_uart_sv:0': Failed to download 'https://github.com/olofk/apb_uart_sv/archive/5309631455a5f41fed5793231ed11ac66ae31e17.tar.gz'. 'Not Found'

ERROR: Failed to fetch '::n25q128a11e:1.2-r1': Failed to download 'https://media-www.micron.com/-/media/client/global/documents/products/sim-model/nor-flash/serial/bfm/n25q/n25q128a_micronxip_hold_18v_vg11,-d-,tar.gz?rev=35e5083ffec64d70ba7d88bb47f55f89'. 'Not Found'

ERROR: Failed to fetch '::at25sf081:1.6': Failed to download 'https://www.adestotech.com/sites/default/files/tools_download/Verilog_AT25SF081.zip'. 'Forbidden'

I propose to change the source of the first one and remove the others (unless they are available somewhere, I could not find them)