arm: rasm2 ignores immediates which are precedeed by an hash

[ghost]

Work environment

Questions	Answers
OS/arch/bits (mandatory)	Linux 5.3.1-arch1-1-ARCH x86_64 GNU/Linux
File format of the file you reverse (mandatory)	N/A
Architecture/bits of the file (mandatory)	arm
r2 -v full output, not truncated (mandatory)	radare2 4.0.0-git 23157 @ linux-x86-64 git.3.9.0-116-g1f6ea1128 - commit: 1f6ea11 build: 2019-10-05__11:54:05

Expected behavior

rasm2 understands the (official?) format for arm immediates #<imm>.

$ rasm2 -a arm -b 64 'STP x29, x30, [sp, #0x80]'
fd7b08a9
$ cstool arm64 fd7b08a9
 0  fd 7b 08 a9  stp    x29, x30, [sp, #0x80]

Actual behavior

rasm2 ignores all immediates which are precedeed by an hash (therefore the (official?) format for arm immediates).

$ rasm2 -a arm -b 64 'STP x29, x30, [sp, #0x80]'
fd7b00a9
$ cstool arm64 fd7b00a9
 0  fd 7b 00 a9  stp    x29, x30, [sp]

Steps to reproduce the behavior

Execute the above instructions

EDIT: in fact, even r2 does ignore them, it makes sense. Editing the title.

$ r2 malloc://16
 -- This code was intentionally left blank, try 'e asm.arch = ws'
[0x00000000]> e asm.arch=arm
[0x00000000]> e asm.bits=64
[0x00000000]> "wa STP x29, x30, [sp, #0x80]"
Written 4 byte(s) (STP x29, x30, [sp, #0x80]) = wx fd7b00a9
[0x00000000]> pd 1
            0x00000000      fd7b00a9       stp x29, x30, [sp]

[ghost]

I am trying to fix it.