Added missing RP2040 definition in Makefile.rtl to make sure that regenerating of Makefiles does not remove rp2040 unit

rtl/embedded/Makefile

@@ -796,6 +796,7 @@ PROFILEUNIT=profile
 RASPI2UNIT=raspi2
 RASPI3UNIT=raspi3
 RASPIUARTUNIT=raspiuart
+RP2040UNIT=rp2040
 RTLCONSTSUNIT=rtlconsts
 SAM3X8EUNIT=sam3x8e
 SAMD51P19AUNIT=samd51p19a

rtl/inc/Makefile.rtl

@@ -444,6 +444,7 @@ PROFILEUNIT=profile
 RASPI2UNIT=raspi2
 RASPI3UNIT=raspi3
 RASPIUARTUNIT=raspiuart
+RP2040UNIT=rp2040
 RTLCONSTSUNIT=rtlconsts
 SAM3X8EUNIT=sam3x8e
 SAMD51P19AUNIT=samd51p19a